The Egyptian tortoise has a relatively small range: mainly the narrow coastal strip along the North African coast from Libya, through Egypt into Israel, extending at the most some 56 miles (90 km) inland. It was discovered in Israel in 1963. The largest population there lives between Beersheba and the Egyptian border; others inhabit scattered areas of the Negev Desert. A field survey in 1994, financed by the Turtle Recovery Program, concluded that it had all but disappeared from its former territory in Egypt, although a few unsurveyed, remote areas may still hold small populations.

Diminishing Numbers
Uncontrolled collecting has been accompanied by severe habitat destruction. In the recent past house building and tourist development have expanded rapidly along the coast over much of the tortoise’s former habitat. Large areas have been reclaimed for agriculture, and programs of road building, irrigation, and sand extraction have been implemented. Many suitable tortoise areas have disappeared forever. Further degradation of the habitat had been caused by the goats and sheep belonging to the wandering Bedouin herdsmen; the animals eat the same plants as the tortoise. Traditionally the Bedouin moved them around on foot when the sparse grazing was exhausted. However, the animals can now be moved using trucks and are taken to remote areas that might have remained untouched.

All species of small tortoise fetch high prices in Britain, Europe, and the United States. Illegal consignments, sometimes including Egyptian tortoises, are occasionally seized. Commercial collection in Egypt has ended due to the lack of tortoises, but they still come in from Libya. The Libyan authorities occasionally crack down at the border, but at one time they were demanding a tax on tortoises taken across. Israel recently banned the export of all its wildlife, but its tortoise populations are under pressure as a result of building development and agricultural expansion.

Tortoise Care

Steps are being taken in Egypt to save the species. In 1997 Tortoise Care was set up after 200 tortoises were seized by Egyptian police. They were given medical treatment, and shelters were built-some tortoises even produced eggs, which were successfully hatched. The project has grown, thanks to local and outside assistance from bodies including the Cairo American College, the Tortoise Trust (an American-British organization), the Danish government, the Netherlands government, and the Zoological Society of London. Captive breeding is under way in Egypt (160 eggs hatched successfully in 1999), and supervised releases using radio-tracking equipment have taken place. The Tortoise Trust and some British zoos are also breeding Egyptian tortoises.

A tortoise sanctuary has been established in a nature reserve at Zaranik on the north Sinai coast, with the help of the Egyptian Environmental Affairs Agency. The sanctuary also includes a visitor center where local Bedouins are employed as guards, and craft items based on the theme of tortoises are sold. Zaranik was formerly part of the Egyptian tortoises’ natural range; although it is listed as an internationally important wetland and is also the Egyptian coast’s largest green turtle nesting site, the area is still under pressure from proposed development. Many Egyptian tortoise specimens are owned by collectors in Europe and the United States, and their young are sometimes offered for sale, particularly in the United States. The legality of such sales varies from one country to another.

The Tortoise Care organization in Egypt is pressing the government to give greater protection to the Egyptian tortoise and its habitats. Its members are also planning to set up more reserves in which the diminutive tortoise may live and breed in safety.

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Egyptian tortoise ( Testudo kleinmanni )

• Family: Testudinidae
• World population: Unknown
• Distribution: North Africa
• Habitat: Arid, sandy areas with sparse vegetation
• Related endangered species: Greek tortoise (Testudo graeca);Hermann’s tortoise; western Hermann’s tortoise; Horsfield’s tortoise
• Size: Length: males up to 3.8 in (9.5 cm); females up to S in (12.7 cm)
• Form: Head, legs, and soft parts light yellow; most specimens bear 2 V-shaped dark marks on the plastron (lower shell)
• Diet: Grasses and annual plants
• Breeding: Typically 1 egg (occasionally 2) laid at monthly intervals until 4 or 5 have been laid

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Many turtles sold in the trade are said to have been farmed, but it is claimed that adults are taken from the wild to replenish breeding stocks. When the yellow-blotched sawbacks were placed on the IUCN Endangered Species List as Threatened in 1991, many aspects of their behavior and biology were unknown. However, recent studies are providing more information. In the wild females tend to live on mollusks, while males prefer aquatic plants, insects, and larvae. Females become mature when they are about 5 inches (13 cm) long, males when they are about 2.5 inches (6.5 cm) long. In zoo collections females have produced small clutches of between one and five eggs, sometimes laying two or three clutches in a year. The low breeding rate is a problem for a declining species.

Toxic Rivers

Yellow-blotched sawbacks are adapted to living in clean, slow- to moderate-flowing rivers where they use the sandy river banks and sandbars for nesting. They like to bask, making use of rocks or fallen logs for the activity. Most turtle species will only bask in warm, sunny weather, but the yellow-blotched sawbacks will bask even when temperatures are low or when it is raining; This behavior leaves them vulnerable to being killed by thoughtless people who use them as target practice. However, today, as in the past, the greatest threat is from habitat alteration and destruction. As human settlement spread, trees along the rivers were felled for timber and the land cleared for building. Turtle nesting and basking sites were lost as sandbars and beaches were excavated to improve navigation. Turtle food was swept away during these activities, and some areas of the river became unsuitable for the turtles because of their greater depth and increased water flow. Industries sprang up along the rivers and began to dump waste products into the water. They killed off food sources, in turn killing off the turtles

Storm water drains, as well as the construction of dams, levees (embankments to protect against flooding), and flood walls have so altered the riversides that determining the original natural habitat of the yellow-blotched turtle is virtually impossible. In many areas increased recreational use of the rivers and adjacent banks is also obstructing efforts to improve the habitat. Camper vans and offroad vehicles also cause problems for nesting turtles. Some reserves have been established-notably the Pascagoula River Wildlife Management Area, which covers 37,000 acres (15,000 ha) of state-protected land in Mississippi. However, pollution threats from upstream still put the turtles at risk.

Protective Measures

The turtle’s future lies in habitat protection and improvement, especially the reduction of effluent. The species is now protected at both state and federal levels. In some areas of turtle habitat roads are gated and entry prohibited, but signs are ignored by collectors and others. Protection against collecting and deliberate killing requires persuasion and education. Captive breeding in zoos and private collections has been successful and could help maintain numbers, as long as this goes hand-in-hand with a conservation program for the turtle’s river habitat.

The yellow-blotched sawback map turtle basks on riverbanks, rocks, and logs, a habit that makes it vulnerable to unscrupulous hunters.

Data:
Yellow-blotched sawback map turtle
Graptemys flavimaculata

• Family: Emydidae
• World population: Unknown
• Distribution: The Pascagoula River system in Mississippi
• Habitat: Rivers with slow to medium currents and sandy banks for nesting
• Size: Males 2.7-4 in (7-11 cm); females 6-7 in (15-17 cm)
• Form: Green-brown shell with yellow blotches; yellow and black stripes on head and limbs; yellowish mark behind each eye; ridge of toothlike projections along back
• Diet: Plants and insects
• Breeding: Between 1 and 5 eggs per clutch; 2-3 clutches per year­
• Related endangered species: Barbour’s map turtle (Graptemys barboun); Cagle’s map turtle (G. caglei); Escambia map turtle (G. ernsti); Pascagoula map turtle (G. gibbonsi); ringed map turtle (G. oculifera); Texas map turtle (G. versa)

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Known locally as buaja daret (”land crocodiles’, these giant lizards were named after the mythical dragon because of their size and fierce predatory nature. It seems inconceivable that the enormous Komodo dragon could remain upknown (at least to western scientists) until the early 20th century. Referred to locally as the ora or buaja daret (”land crocodile”), early reported sightings were probably dismissed as superstition or simply as crocodiles. In 1912 a Dutch pilot, having swum ashore to the island of Komodo after crashing in the sea, reported seeing them; further investigation verified their existence. The first scientific description was by Major P. A. Ouwens, director of the botanical gardens in Buitenzorg, Java, in 1912. Soon afterward a government order closed the area in which they were found and limited the number of specimens allowed to go to zoos. The Komodo dragon is found only on Komodo and the neighboring islands of Rinca, Padar, and western Flores. Some of the populations are probably transient they are powerful swimmers and go from island to island in search of food. The total area of their natural habitat is roughly 390 square miles (1,000 sq. km), and it is generally hot, with an average daytime temperature of 80°F (27°C) or higher. Usually conditions are very dry, too, apart from a short monsoon season, when the Komodo dragons use pools caused by rain for wallowing.

During hot weather and overnight they take to burrows. Komodo dragons are top predators in their range. Adults will tackle anything, including deer, pigs, and goats. Occasionally even humans are said to feature in the diet. They are armed with a strong tail as well as powerful limbs and claws. Their teeth are serrated like those of sharks and can easily rip a carcass. They also produce bacteria that cause blood poisoning and death. Prey that is not killed immediately often dies later. Komodo dragons can scent the carrion up to 5 miles (8 km) away and come to gather at the site of the death. The Indonesian government regards Komodo dragons as a national asset, and they are protected. Hunting is strictly forbidden; trade in Komodos (or their parts) is banned under CITES. Tourists on Komodo are carefully controlled to prevent disturbance. The islands of Radar and Rinca are nature reserves where no tourists are allowed. However, Komodo dragons have been smuggled. In 1998 a Malaysian was arrested in Mexico City after investigation by the United States Fish and Wildlife Service, and Komodo dragons were seized.

Protecting the Species

The main threat to Komodo dragons comes from habitat destruction and the poaching of their prey by inhabitants on Komodo Island. Radar and Rinca are uninhabited, so this is not a problem; however, there, as on Komodo, natural fires destroy the plants and animals on which the dragons depend. Recent reports claim that many specimens on Komodo are emaciated from lack of food. The first captive-breeding attempt was carried out in the National Zoo, Washington, in 1992, when 13 out of a clutch of 26 eggs hatched; this was followed by two successful hatchings at Cincinnati Zoo in 1993.

Currently around 300 specimens are held in zoos worldwide; 186 of the specimens are juveniles bred in captivity. This is encouraging, but many zoos are unable to set up breeding groups due to lack of space. Zoo populations are seen as a “reservoir” from which specimens could be reintroduced into the wild. No further introductions will be made, however, until the genetic makeup of wild and captive-bred specimens has been studied, since variations between the two have been observed. The Komodo dragon is a giant lizard about 8feet (2.4 m) long. The largest recorded example, which was displayed in Saint Louis in the 193 0s, measured 10.2 feet (3 m) and weighed over 350 Bounds (160 kg).

Komodo dragon
Varanus komodoensis

• Family: Varanidae
• World population: 3,000-5,000 in the wild
• Distribution: Indonesia; islands of Komodo, Rinca, Padar, and western Flores
• Habitat: Lowland islands, aril forest, and savanna
• Size: Length: males over 8 ft (2.4 m); females 7 ft (2.1 m). Weight: males 200 lb (90 kg); females 150 lb (67 kg)
• Form: Lizard with large, bulky body and powerful tail, strong limbs, and claws. Rough scales give a beaded appearance. External ear openings are visible on each side of the head. Sharp teeth for ripping carcasses. Coloration is brown, black, reddish brown, or gray
• Diet: Hatchlings and juveniles eat insects, reptiles, eggs, small rodents, and birds. Adults eat deer, pigs, goats, possibly water buffalo, and reputedly, humans
• Breeding: Up to 30 eggs, buried. Incubation period about 8 months
• Related endangered species: Gray’s monitor lizard (Varanus olivaceus)

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Before permanent settlers arrived on the Galapagos Islands in the 1830s, there were huge numbers of giant tortoises. Since then habitat destruction and immigrant predators have taken their toll. Lying off the coast of Ecuador and almost on the equator, the Galapagos Islands achieved lasting fame after the English naturalist Charles Darwin published his theory of evolution in The Origin of Species (1859). The book was written after his visit to the islands in 1835. The area was already well known to whalers and other seamen who, between 1789 and 1860, took tortoises to keep on their ships as sources of fresh meat. The tortoises, with water stored in their bladders, would survive on the ships for several months until they were needed. Whaling declined after 1860, when petroleum started to be used instead of whale oil for lighting. Apart from humans, the tortoises had no predators except some birds, which took hatchlings. Galapagos tortoises are the largest in the world. One male specimen measured 4.3 feet (1.3 m) and weighed about 425 pounds (200 kg). There is considerable variation in the shape of the shell, depending on which island they inhabit, a phenomenon that was noted by Darwin and helped form his theories.

Some tortoises have domed shells; others have “saddleback” shells that allow the head to be raised higher. The length of the neck and size of the head also vary; they were considered to be a single species, but scientific study showed that there were 15 different “races” from the various islands, and each one has a third name to distinguish it from others. Three races are now extinct, and some of the others are very rare. When settlers came to the islands in the 1830s, they brought pigs, goats, dogs, cattle, and burros (donkeys), some of which escaped and began to breed, causing a further decline in tortoise numbers. Pigs and dogs eat eggs and hatchlings; the other animals destroy the vegetation and trample tortoise nests. Rats and fire ants, both introduced species, also eat large numbers of hatchlings. In 1928 a New York Zoological Society expedition collected 180 tortoises and allocated them to zoos as far away as Australia. Some of them have bred to second generation, and one from San Diego zoo was returned to the islands for a captive-breeding program. Following pressure from scientists, the Charles Darwin Foundation was formed in 1959, followed in 1964 by the Charles Darwin Research Station. The islands became a national park, and laws were passed to prevent the removal of any animals.

Long-Term Plans It is estimated that some islands may need 100 years to recover their vegetation and tortoise populations. The recovery program instituted by the research station has included collecting eggs from the wild and incubating them artificially, and removing introduced animals. The first young were released in 1970. Collecting eggs in the wild for incubation has progressed to breeding some tortoises at the research station. The first hatchlings were released in 1975, and in 1991 the first wild-bred hatchling was found on the island. The highlight of the program was the release, early in 2000, of the thousandth tortoise on Espanola.

The tortoise population of the islands has almost doubled in recent years, and laws have been passed to restrict settlement and protect the coastal waters. Quarantine laws forbid the introduction of nonnative plants and animals. One problem was that some of the races had been reduced to very low numbers, and their lack of genetic diversity was a cause for concern. Even today it is possible that more tortoises may be found on islands where populations are low. This would seem to be the only hope for a tortoise nicknamed Lonesome George, the sole survivor of a race from Pinta Island. He was discovered in 1971 and moved to the station with two females of another race, but as yet no eggs have been produced, and no Pinta female can be found. Galapagos giant tortoises are now rare or extinct on many of the islands because of habitat destruction and the introduction of animals thatprey on the young or compete with adults for food.

Statistics: Galapagos giant tortoise Geochelone nigra

• Diet: Almost any green vegetation
• Family: Testudinidae
• World population: About 10,000
• Breeding: About 7-20 eggs buried in soil
• Distribution: Galapagos Islands, Pacific Ocean
• Habitat: Volcanic islands; hot and dry with rocky outcrops; some forested areas with grassy patches
• Size: Length: up to 4 ft (1.2 m). Weight: up to 500 (b (227 kg)
• Form: Huge tortoise with gray-brown shell and hard­scaled legs; some have domed shells; others are saddleback (resembling a saddle in shape)
• Related endangered species: All subspecies of Geochelone nigra are on the IUCN Red List, including the Abingdon Island tortoise (Geochelone nigra abingdoni) EW; Duncan Island tortoise (G. n. ephippium) EW; Charles Island tortoise (G. n. galapagoensis) EX; Hood Island tortoise (G, n. hoodersis) CR. The Brazilian giant tortoise (G. denticulata) is VU

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Most insects begin their independent lives as fertilized eggs. The chorion, or eggshell, is commonly pierced by respiratory openings that lead to an air-filled meshwork inside the shell. For some insects (e.g., cockroaches) a batch of eggs is cemented together to form an egg packet or ootheca. Insects may pass unfavourable seasons in the egg stage. Eggs of the lucerne flea Sminthurus (Collembola) and of some grasshoppers (Orthoptera) pass summer droughts in a dry shrivelled state and resume development when moistened. Most eggs, however, retain their water although they may pass the winter in a state of arrested development, or diapause, usually at some early stage in embryonic development.

Dried eggs of Aedes mosquitoes enter a state of dormancy after development is complete; they quickly hatch when placed in water. The hatching of young larvae is achieved in several ways. Some, such as caterpillars, bite their way out of the egg. Many, such as the flea, have hatching spines with which they cut a slit in the shell; others force off a preformed egg cap. In order to exert this force, the young larva swallows air; after hatching, it continues to distend itself in this way until the cuticle hardens. Once formed, the insect cuticle cannot grow. Growth can occur only by a series of molts (ecdyses) during which new and larger cuticles form and old cuticles are shed. Molting makes possible large changes in body form.

Types of metamorphosis

In the most primitive wingless insects (apterygotes) such as the silverfish Lepisma, there is almost no change in form throughout growth to the adult. These are known as ametabolous insects. Among insects such as grasshoppers (Orthoptera), true bugs (Heteroptera), and homopterans (e.g., aphids, scale insects), the general form is constant until the final molt, when the larva undergoes substantial changes in body form to become a winged adult with fully developed genitalia. These insects, termed hemimetabolous, are said to undergo incomplete metamorphosis. The higher orders of insects i.e., Lepidoptera (butterflies and moths), Coleoptera (beetles), Hymenoptera (ants, wasps, and bees), and Diptera (true flies) are termed holometabolous because larvae are totally unlike adults. These larvae undergo a series of molts with little change in form before they enter into complete metamorphosis, which includes molting first into pupae and then into fully winged adults.

Types of larvae

Larvae, which vary considerably in shape, are classified in five forms: eruciform (caterpillar like), scarabaeiform (grublike), campodeiform (elongated, flattened, and active), elateriform (wireworm like), and vermiform (maggot like). The three types of pupae are obtect, with appendages more or less glued to the body; exarate, with the appendages free and not glued to the body; and coarctate, essentially exarate but remaining covered by the cast skins (exuviae) of the next to the last larval instar (name given to the form of an insect between molts).

Role of hormones

Both molting and metamorphosis are controlled by hormones. Molting is initiated by a hormone from neurosecretory cells in the brain. The hormone acts upon a prothoracic gland, an endocrine gland in the prothorax; this gland, in turn, secretes the molting hormone, a steroid known as ecdysone, which, by its action on the epidermis, stimulates growth and cuticle formation. Metamorphosis likewise is controlled by a hormone. Throughout the young larval stages a small gland behind the brain, called the corpus allatum, secretes the juvenile hormone (also known as neotenin).

So long as this hormone is present in the blood the molting epidermal cells lay down a larval cuticle. In the last larval stage, juvenile hormone is no longer produced, and the insect undergoes metamorphosis into an adult. Among holometabolous insects the pupa develops in the presence of a very small amount of juvenile hormone. Although a state of arrested development may occur during any stage, diapause occurs most commonly in pupae. In temperate latitudes many insects overwinter in the pupal stage (e.g., cocoons). The immediate cause of diapause, failure to secrete the growth and molting hormones, usually is induced by a decrease in daylength as summer wanes. In addition to the changes in form during development, many insects exhibit polymorphism as adults. For example, the worker and reproductive castes in ants and bees may be different; termites have a soldier caste as well as reproductives and persistent larvae; adult aphids (Homoptera) may be winged or wingless; and some butterflies show striking seasonal dimorphism. The general interpretation of all such differences is that, although the capacity to develop different forms is present in the genes of every member of a given species, particular lines of development are evoked by environmental stimuli. Hormones, including perhaps the juvenile hormone, may be agents for the control of such changes.

Reproduction

The life of the adult insect is geared primarily to reproduction. Since reproduction is sexual in almost all insects, mating must be followed by impregnation of the female and fertilization of eggs. Usually the male seeks out the female. In butterflies in which vision is important, the colour of the female in flight can attract a male of the same species. In mayflies (Ephemeroptera) and certain midges (Diptera) the males dance in swarms to provide a visual attraction for females. In certain beetles (e.g., fireflies and glowworms) parts of the fat body in the female have become modified to form a luminous organ that attracts the male. Male crickets and grasshoppers attract females by their chirping songs, and the male mosquito is lured by the sound emitted by the female in flight. The most important element in mating, however, is odour. Most female insects secrete odorous substances called pheromones that serve as specific attractants and excitants for males. The male likewise may produce scents that excite the female.

Certain scales (androconia) on the wings of many male butterflies function in this way. Assembling scents, active in small quantities, are well known in female gypsy moths and silkworms as male attractants. The queen substance in the honeybee serves the same purpose. Mating and egg production require appropriate temperatures and adequate nutrition. The need for protein is particularly important, and in insects such as Lepidoptera (butterflies and moths), which take only sugar and water in the adult stage, necessary protein is derived from larval reserves. Temperature and nutrition often influence hormone secretion. Juvenile hormone or hormones from the neurosecretory cells commonly are needed for egg production. In the absence of these hormones reproduction is arrested, and the insect enters a reproductive diapause. This phenomenon occurs in the potato beetle Leptinotarsa during the winter. A few insects (e.g., the stick insect Carausius) rarely produce males; the eggs develop without fertilization in a process known as parthenogenesis. During summer months in temperate latitudes, aphids occur only as parthenogenetic females in which embryos develop within the mother (viviparity). In certain gall midges (Diptera) oocytes start developing parthenogenetically in the ovaries of the larvae; the young larvae escape by destroying the body of their mother in a process called paedogenesis.

Sensory perception and reception

Touch

Insects have an elaborate system of sense organs. Tactile hairs, concentrated on the antennae, palps, legs, and tarsi, cover the entire body surface. The hairs serve to inform the insect about its surroundings and its body position (a phenomenon known as proprioception). For example, contact between the hairs on the feet and the ground inhibits movement and may lead to a state of sleep in some insects. Modified mechanical sense organs in the cuticle called campaniform organs detect bending strains in the integument. Such organs exist in the wings and enable the insect to control its movements. Campaniform organs, well developed in small clublike halteres (the modified hind wings of dipterans), serve as strain gauges and enable the fly to control its equilibrium.

Sound

Exceedingly sensitive organs called sensilla are concentrated in organs of hearing—e.g., bushy antennae of the male mosquito or tympanal organs in the front legs of crickets or in abdominal pits of grasshoppers and many moths. In moths these sensitive organs can perceive the high-pitched sounds emitted by bats as they hunt by echolocation. Insects complement organs of sound reception with sound-producing organs, which usually are (as in crickets) wing membranes that vibrate in response to movement of a stiff rod across a row of stout teeth. Sometimes (as in cicadas) a timbal (membrane) in the wall of the thorax is set in vibration by a rapidly contracting muscle attached to it.

Chemicals

Chemical perceptions by the thin-walled sensilla may be comparable to the human sense of taste or smell. Many insect chemoreceptors are specialized according to specific behaviour patterns. For example, although approximately equivalent to humans in the perception of flower odours and sugar sweetness, honeybees are exceedingly sensitive to the queen substance, which is scentless to humans. And male silkworm moths are excited by infinitesimal traces of the female sex pheromone, even in the presence of odours that are intensely strong to humans.

Sight

Although the insect eye provides very poor form perception, insects by using a process of scanning (i.e., moving the eye rapidly across a field of view) probably can form adequate visual impressions of their surroundings. Insects have good colour vision; colour perception commonly extends (as in ants and bees) into the ultraviolet, although it often fails to extend into the deep red. Many flowers have patterns of ultraviolet reflection invisible to the human eye but visible to the insect eye.

Behaviour
Instincts

The insect orients itself by making orientation responses to the stimuli it receives. Formerly, insect behaviour was described as a series of forced movements in response to stimuli. That hypothesis has been supplanted by one that holds that the insect has a central nervous system with built-in patterns of behaviour or instincts that can be called forth by environmental stimuli; these instincts are modified by the insect’s internal state, which has been affected by preceding stimuli. Searching for food or an egg-laying site, catching prey, and mating are a few examples of complex behaviour. Experimental studies of details of behaviour have provided significant information about the properties of the sense organs. Patterns of behaviour range from comparatively simple reflex responses (e.g., the avoidance of adverse stimuli, the grasping of a rough surface on contact with the claws) to the elaborate behavioral sequences involved in hunting, capturing, and eating prey. The highest developments of behaviour, found in social insects such as the ants, bees, and termites, are based on the instinct principle.

An interesting example of a behavioral pattern is that found in the leaf-cutter bee Megachile. The female bee first locates a site for her nest in rotten wood and shapes the nest into a long tunnel; then she seeks out preferred shrub leaves from which to build a cell and cuts first a disc for a cell cap, then a series of oval pieces for the walls. After preparing the nest, she stores a mixture of pollen and honey, lays an egg, and finally closes the cell with more cut leaves. The leaf-cutter bee repeats this sequence until the nest is filled. Each act can be performed only in this set sequence. The insect does not stop to repair any damage to the nest but proceeds undeterred to the next step in her behavioral pattern. The honeybee society is more flexible than that of the leaf-cutter bee. Behavioral sequences of individuals are predictable, but the choice of acts or duties within the hive can be influenced by the needs of the colony. A capacity for learning does exist, and must exist, in any insect that has to find its nest; but learning capacity plays a relatively small part in the overall pattern of honeybee behaviour.

Insect societies

Both in complexity of behaviour and learning capacity, solitary bees and wasps are the equals of social wasps or honeybees. Social insects, however, have developed a division of labour in which the members must do the work required at the proper time. If the society is to succeed, its needs must be communicated to the individual, and the individual must act. These needs may be met by a temporary change in behaviour during which appropriate instinctive acts are performed or by changes in development that lead to the appearance of appropriate castes. Commonly, both behavioral and developmental changes are initiated by pheromones, which act as chemical messengers that convey information from one member of a colony to another.

Insect societies are gigantic families, the offspring of a single female. In the honeybee the single queen in the hive secretes the pheromone known as the queen substance (oxodecenoic acid); it is taken up by the workers and passed throughout the colony by food sharing. So long as the queen substance circulates, all members are informed that the queen is present. If the workers are deprived of queen substance, they proceed at once to build queen cells and feed the young larvae with a special salivary secretion known as royal jelly to produce more queens. Pheromones liberated by termite soldiers or reproductive adults control the development of soldiers and reproductive forms. Alarm substances and other pheromones control much of the behaviour in ants. A remarkable form of communication is the dance language in the honeybee, in which the direction and approximate distance of a foraging site can be conveyed by one worker to another. For additional information on the social behaviour of bees, ants, and termites, see below in sections on the Hymenoptera and the Isoptera.

Ecology
Terrestrial insects

Insects feed on every sort of organic matter, and their methods of feeding and digestion have become modified accordingly. The major climatic hazards faced by terrestrial insects are temperature extremes and desiccation. Different species function best at various optimal temperatures. If conditions are too hot, an insect seeks out a cool, moist, and shady spot. If exposed to the sun, an insect positions itself so as to present the smallest amount of body surface to the heat. If conditions are too cool, insects remain in the sun to warm themselves. Many butterflies must spread their wings to collect heat before they can fly. A moth raises its temperature by vibrating its wings or “shivering” before taking flight.

The heat generated in this way is conserved by hairs or scales that maintain an insulating layer of air around the body. The optimum muscle temperature for flight is from 38° to 40° C (100° to 104° F). In extremely cold weather the danger for insects is freezing, and insects that survive winters in cold latitudes are called cold hardy. A few insects (e.g., some caterpillars and aquatic midge larvae) tolerate ice formation in body fluids, although it is probable that the cell contents do not freeze. In most insects, however, cold hardiness means resistance to freezing. This resistance results partly from accumulation of large quantities of glycerol as an antifreeze and partly from physical changes in the blood that permit supercooling, without freezing, to temperatures far below the freezing point. Resistance to desiccation includes development of hard waterproofing waxes and exaggeration of water-conserving mechanisms.

Aquatic insects

Major adaptational changes apart from remarkable modifications of the legs for swimming concern respiration of aquatic insects. Some occur in insects that rise to the water surface to take atmospheric air into their tracheal systems. Mosquito larvae use only the last pair of abdominal spiracles, which open at the tip of a respiratory siphon. Water beetles (e.g., Dytiscus) have converted the space between the protective sheaths on the hind wings (elytra) and the abdomen into an air-storage chamber. Air-breathing insects can prolong the period of submergence by trapping air among their surface hairs. This air film acts as a physical gill and makes possible oxygen uptake from water. Other adaptations to an aquatic environment have occurred in larvae that obtain all their oxygen from the water. In midge larvae, abundant tracheae (breathing tubes) supply the entire thin cuticle. Caddisfly larvae (Trichoptera) and mayfly larvae (Ephemeroptera) have tracheal gills. In large dragonfly larvae, the gills are inside the rectum, and the water is pumped in and out through the anus.

Protection from enemies

Insects may derive some protection from a horny or leathery integument; but they also have various chemical defenses. Some caterpillars carry among their body-surface hairs special irritating hairs, which break up into barbed fragments containing a poisonous substance that causes intense itching and serves as a protection against most birds. Dermal glands of many insects discharge repellent or poisonous secretions over the cuticle; other insects are protected by poisons that are present continuously in the blood and tissues. Such poisons often are derived from the plants on which the insects feed.

In many hymenopterans (ants, bees, wasps) accessory glands of the female, which usually pour out a secretion over the egg, have become modified to produce toxic proteins. These poisons, injected into the nervous system of the prey of solitary wasps, paralyze it; in this state the prey serves as food for the wasp larva. Similar stings are used by hymenopterans, including ants, wasps, and bees, for self-defense. Concealment is an important protective device for insects. Vast numbers hide beneath stones or the bark of trees. Others rely on protective coloration. Although insect colours depend partly on pigmentation in the outer body covering (cuticle), the most important pigments occur in epidermal cells below the cuticle. Butterfly and moth pigments are deposited inside flattened hairs, or scales, which cover the wings. Some of the most brilliant insect colours are not the result of pigmentation; they are physical interference colours produced by fine laminae in the surface of the scales. Protective coloration may take the form of camouflage (cryptic coloration) in which the insect is confused with its background. The coloration of many insects copies a specific background with extraordinary detail. Stick insects (Carausius) can accommodate their colour to that of a changing background by moving pigment granules in their epidermal cells. Some caterpillars have patterns that develop in response to a background; however, these are irreversible. Insects such as caterpillars, which rely on cryptic coloration, combine it with a rigid deathlike position. Alternatively, insects that are well provided with chemical defenses generally show conspicuous warning, or aposematic, coloration. Experiments have proved that predators such as birds quickly learn to associate such coloration labels with nauseous or dangerous prey. Finally, insects without nauseous qualities may gain protection by mimicry, that is, by developing the conspicuous coloration found in distasteful species (see also coloration; mimicry).

Population regulation

The factors that limit the numbers of insect species are complex. Experimental studies of a population of grain beetles in a jar containing wheat show that the complexities increase if a second species is added. With insects in natural habitats, competing not only with members of their own species but with numerous other species as well, the obstacles to survival become increasingly great. Competition among species is reduced to some extent by adaptation of species to niches, or habitats, for which other insects do not compete. Formerly, controversy arose over whether numbers were always density dependent (i.e., limited by the density of the species itself) or whether catastrophic actions, notably the vagaries of weather, were often of prime importance. It has since become recognized that the ultimate factor in the control of numbers is competition within the species for food and other needs; but in many circumstances, before competition for food becomes significant, numbers are reduced by external factors.

Competition within a species often is reduced by wholesale migration to new localities. Migration may occur by active flight, as in aphids and locusts, largely directed by the wind. Another important factor in the regulation of populations is balanced polymorphism of species, in which the prevalence of individuals with given characteristics changes according to the action of natural selection as the state of the environment changes.

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The decline of this attractive lizard dates back to the California Gold Rush of 1849, when parts of its habitat were turned over to agriculture to feed the influx of miners. The habitat of the blunt-nosed leopard lizard is now restricted to a number of scattered areas in the San Joaquin Valley in California. The lizards use the deserted burrows of small mammals for shade, shelter, and hibernation in winter. Although they are diurnal (active during the day), leopard lizards tend to shelter during the hottest part of the day. They are often active at air temperatures of up to 104°F (40°C), when the soil temperature is about 122°F (50°C). From September onward the lizards take to their burrows to spend the colder months in a dormant state. Leopard lizards have predators, which is part of the natural balance; but when the lizards are forced into smaller areas by human disturbance, and their vegetation cover is destroyed, they become more exposed and vulnerable to these predators.

The Human Threat

As the human population increased in the San Joaquin Valley, so did agriculture and urban development. This inevitably encroached on the habitat of the blunt-nose leopard lizard. Further damage occurred as industries developed around the extraction of oil and minerals. By 1985 barely 10 percent of the original wild land on the San Joaquin Valley floor had been left undeveloped. The road building and landfill dumping that accompanied development in the valley were also destructive to the lizard’s habitat, and the damage to the delicate balance of the desert ecosystem largely ignored. Lizards and their habitats were destroyed under construction machinery; roads and irrigation ditches fragmented the lizard’s territory. Pesticides sprayed on crops also had a detrimental effect on much of the wildlife. Leopard lizards are insectivorous-a large part of their diet includes insects-so their food supply can be drastically reduced, or contaminated, by the drift from crop spraying. Where the land has been adapted for pastoral farming, grazing animals eat the natural vegetation and trample rodent burrows and lizard egg sites. They also break the soil surface, which can cause soil erosion. The removal of natural vegetation through grazing allows nonnative plants to invade, eliminating, the open spaces preferred by the lizard. The threats to the blunt-nosed leopard lizard from continuing habitat destruction were highlighted as far back as 1954, but the species was not listed as endangered by the United States Department of the Interior until 13 years later. It was given state listing in 1971.

Recovery Plans

The first recovery plan for the species was not prepared until 1980 (revised in 1985). Since then numerous studies have been carried out, including aerial surveys, to determine the amount of suitable territory still existing. Some areas have been purchased as reserves, but lack of funding has prevented this in many areas. Conservation is a complex business needing comprehensive studies of numerous aspects: ecology, population, feeding habits, breeding, and genetic variability. Although much information has now been gathered, the scattered nature of the remaining lizard sites complicates matters because of environmental variation. It may be a long time before all the necessary knowledge is accumulated. The blunt-nosed leopard lizard has proved itself to be adaptable, often colonizing sites that have been disturbed then abandoned. However, unless the decline of its habitat and its continued isolation in ever-shrinking areas are halted, the species may never recover. Its survival depends on further land acquisition and the construction of “corridors” to allow groups to move between fragmented sites, so preventing the genetic problems that develop in small populations. Its habitat must be protected, improved, and managed in such a way that the land is only used in a manner compatible with the lizard’s existence. This is a tall order given the conflicting interests over land use. Recovery of this species will take a very long time; it remains to be seen if it will be successful.The blunt-nosed leopard lizard is active by day and prefers hot, dry, and sparsely vegetated areas. It can run on its hindlegs to escape predators, which include snakes, birds, and mammals.

Statistics

• Family: lguanidae
• World population: Unknown
• Distribution: San Joaquin Valley,California
• Habitat: Arid areas, often alkaline, saline or sandy soils with sparse vegetation, rarely above 2,500 ft (800 m)
• Diet: Mainly insects, other lizards, and small mammals
• Breeding: One clutch of 2-6 eggs laid per year
• Related endangered species: None
• Size: Length: up to 13 in (33 cm)
• Form: Slender lizard with long, “whippy” tail, blunt nose, and spotted throat; variable pattern of dark spots and light bars on yellow, fawn, gray, or dark- brown background; body color lightens with increased temperatures, so spots become indistinct; mated females and juveniles develop orange spots; males have red coloration in the breeding season

Tags: animal, animals, bird, cat, insect, mammal

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The pygmy blue-tongued skink-once a common lizard-was presumed to be extinct, since there had been no sightings after 1959. In 1992, however, one was found inside the body of a dead snake. Surveys carried out in the surrounding region-the grasslands of South Australia’s Mount Lofty Ranges-revealed a dozen small sites containing pygmy blue-tongued skinks.AIthough less than half the size of the larger blue-tongued skinks familiar to many reptile keepers, the pygmy blue-tongued skink is otherwise similar in appearance. Its common name comes from the blue tongue displayed by most lizards of the genus Tiliqua. However, while the pygmy skink’s mouth lining is pinkish-blue, its tongue is actually pink. The dramatic color combination provides a startling effect that deters attackers. The lizard is found in the Mount Lofty Ranges north of Adelaide in South Australia. Unfortunately, the animal’s preferred habitat is also highly suitable for farming. The climate is ideal, and the native grassland can be easily plowed. Pasture improvement-a process of replacing native plant species with agricultural species such as hay grasses and crops like alfalfa and clover-has further altered the plant diversity in favor of nonnative species.

Habitat Destruction

At the time when the lizards are most active-during the warm months-the soil is too hard for them to dig their own burrows. As a result, they often live in empty spider burrows dug by the spiders during the winter and early spring, when the soil is moist and soft. Plowing of the land is likely to be particularly destructive to the skink’s survival, depriving them of shelter and leaving them exposed to snakes, birds, and other predators. Before Europeans settled in South Australia, much of the area was native grassland supporting other reptile species, as well as birds and plants. Now only about 2 percent of the original grassland is left. All pygmy blue-tongued sites are found in the few unplowed areas. The undisturbed patches also support rare orchids and other plants, butterflies, and an endangered bird: the plains wanderer. Conserving the remaining grasslands will benefit the pygmy bluetongues as well as the other rare fauna and flora.

Conservation Projects

The discovery of an extinct species was exciting, and various government bodies, museums, zoos, and universities cooperated in the search for new habitat sites. A recovery plan was devised; its first task was to study skinks in the wild and in captivity. A group of pygmy blue-tongued skinks was taken to Adelaide Zoo to be studied. Specimens were also displayed to increase public awareness of the lizard’s plight. After seven years in captivity the colony had not bred. It was decided to set up another group in private, free from disturbance by the public. Little was known about the animal’s behavior and requirements, but captive breeding for possible release into the wild was an important part of the recovery plan. Pygmy blue-tongues are listed under the Endangered Species Protection Act and the South Australia National Parks and Wildlife Act. An important task has been to persuade landowners to protect known skink habitat sites on their land. There are also several laws that could be enforced to prevent habitat destruction. Law enforcement is perhaps the most important task, since the habitat is fragile and small in area. Recently owners of land enclosing three habitat sites signed a 10-year agreement to run their properties as wildlife sanctuaries. Other landowners are eager to sign up, but legal problems over grazing rights have caused some delay. Two previously unknown sites have also been discovered, although they are at some distance from the existing sites. By early 2000 the situation for the pygmy bluetongue skink had improved. An area of native grassland-unpopulated by the species but close to its other habitats-was made into a conservation park in the hope that it will be suitable for translocations. The park could be the first secure home for the animals. The total number of blue-tongues is difficult to estimate because of their patchy distribution, but it may be about 5,500. However, the figure is still too low to justify changing the lizard’s endangered status to Vulnerable. Although relatively few populations are unprotected now, the lizard will keep its status until larger populations exist in secure habitats. One project to increase numbers involves the provision of artificial burrows. They are made from wooden tubes that are the same length and diameter as the favored spider hole, but less easily destroyed. Advising landowners on habitat management, such as weed clearance, grazing, and the use of pesticides, is also an important part of the program. Community involvement is a high priority, and a local school has been involved in studies as part of the plan. Despite such efforts, the outlook for the pygmy blue-tongued skink is by no means certain, since funds for wildlife conservation are limited.

Pygmy blue-tongued skink
Tiliqua adelaidensis

• Family: Scincidae (subfamily Lygosominae)
• World population: About 5,500
• Distribution: North Mount Lofty Ranges, southern South Australia
• Habitat: Grassland with tussocks and open areas; open woodland
• Size: Length: 7 in (18 cm); males often slightly smaller than females
• Form: Heavy body with relatively short limbs; scales small and smooth. Male has larger head than female. Color varies from gray-brown to orange¬brown with darker flecks along back
• Diet: Insects and some plant material
• Breeding: Gives birth to 1-4 live young per year

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The Nile crocodile is found in rivers, lakes and swamps throughout Africa south of the Sahara and along the Nile Valley south of Egypt. There is also a small population in Madagascar. Dressed in a suit of bony plates and looking like an armoured tank, the Nile crocodile could be a creature from prehistoric times. With a long tailused to propel it at speed through the water and large jaws, lined with 60 or so pointed teeth, this reptile is a lethal hunting machine. Despite its name, the Nile crocodile is found in most of Africa. Living in lakes, rivers and swamps and sometimes along beaches and even 10 km out to sea – these crocodiles seldom venture far from water. Only if their pool dries up will they trek overland in search of a new aquatic home.

Crafty Predator

Crocodiles are meat eaters, taking fish, turtle and any mammal including zebra, young hippos, big cats and even people. Hatchlings eat small prey like frogs and insects. Adults use a range of hunting techniques, from rushing at prey to herding schools of fish into bays with their tails. They also lie in wait near the shore, with only eyes above water, waiting for animals to come to drink. The unwary fall victim to sudden lunge in which the crocodile seizes the preys head between its huge jaws, or fells it with a whip like blow of the tail. To feed, it rolls over in water with its prey until a piece of the animals flesh is torn off. Amazingly, the Nile crocodile can go without food for up to a year.

Part of bodies

• Eyes and nostrils on top of the head enable the crocodile to observe potential prey and breathe while its body is concealed under the water.
• Third eyelid helps to protect the eyes when underwater
• Feet and claws are for climbing river banks and digging nests
• Enormous tail acts as a powerful paddle when swimming
• Skin ranges from drab green to brownish or blackish green, providing it with excellent camouflage.
• Outer ears close to keep out water when the crocodile dives
• Large jaw opens very wide, allowing the crocodile to catch sizeable prey

Statistics

• status – common
• length – 3.5-6 m
• weight – up to 900kg
• habit – mostly aquatic
• sexual maturity – 8-12 days everage
• number of eggs – 50 everage; up to 100 recorded
• diet – fish and turtles, mammals from small monkeys and antelope to young big cats and humans
• lifespan – 70-100 years

Myth or fact

In spite of the powerful bite of this animal, the muscles that open a crocodiles jaws are, in fact, relatively weak. People who wrestle with crocodiles at tourist attractions may look as though they are strong, but they only need to hold the crocodiles mouth shut with their hands – the animals jaw muscle are not strong enough to force the mouth open.

Tags: animal, animals, cat, fish, insect, mammal

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For centuries the hawksbill’s attractive shell has been the main source of tortoiseshell. Despite international legislation, illegal trade in this commodity continues, and the hawksbill is one of the most seriously threatened sea turtles in the world. Sea turtles such as the hawksbill have always been exploited by humans for food, oil, and skins. On a local scale a balance can be maintained, but the pressure of human activities over the last 50 years has resulted in all sea turtle species becoming endangered. For many years the hawksbill’s attractively colored shell has been the main source of tortoiseshell, used for glasses frames, combs, ornaments, and jewelry. The scutes (hornlike shields) of the hawksbill shell are exceptionally thick, making them ideal for carving. Japan has been the largest user, importing an average of 30 tons (305 kg) of shell per year between 1970 and 1994. More than half of this was from the Caribbean-particularly Cuba-and Latin America. In the 1980s Japan’s stockpile of hawksbill shell represented the death of over 170,000 turtles. Although a member of CITES, Japan did not ban shell imports until 1993. Proposals by Cuba to allow the exportation of hawksbill shell to Japan by transferring the species from CITES Appendix I to Appendix II were defeated in 1997 and 2000. However, turtle meat and eggs are still consumed and sold in many countries. Illegal shipments of shell are often intercepted, and tourist souvenirs, including whole turtles, stuffed and lacquered, are openly traded in many countries. Bringing any part of a sea turtle back from vacation is illegal, and seizures, sometimes followed by fines, are common. Hawksbill have been recorded on the coasts of at least 96 different countries, and nesting takes place only on sandy beaches. Suitable sites exist in the Caribbean (particularly Puerto Rico), Central and South America, and Florida. In at least two of their former haunts the species is now thought to be extinct. Often four or more clutches-of up to 140 eggs each-are laid, usually overnight. This process takes up to three hours, during which time the females and their eggs are vulnerable to predators, including people. An interval of two or three years occurs between each breeding. Hawksbill take at least 30 years to mature to breeding age, a factor that badly affects the replenishment of the population.

Human Interference

Although classed as endangered since 1970, the hawksbill’s situation has not improved. Estimates of the worldwide population are impossible to arrive at, but observers who monitor breeding females in various countries are convinced that numbers are falling. Even without human interference sea turtles’ eggs and hatchlings face severe predation from wild pigs, monitor lizards, crabs, dogs, and seabirds. Humans multiply the threats. The sandy beaches needed for turtle nesting are encroached on by building, mainly for tourist facilities. Beach leveling and mechanical raking can destroy nests, while offroad vehicles compact the sand, crushing eggs and producing tire tracks that prevent hatchlings reaching the sea. People simply walking on nesting sites, especially at night, deter nesting female turtles and compact the sand. In addition, artificial lighting along beaches has increased, and hatchlings that would naturally head toward the light on the horizon at sea instead make for the shore lights and die from either dehydration or predation. Other threats come from fishing nets and lines. Some countries insist on turtle-excluder devices on the nets, but they are not always used. Turtles are often killed or mutilated by boat propellers. Pollution by sewage, pesticides, and other chemicals causes further problems. The hawksbill is gravely endangered by the destruction of coral reefs from silting and excavation for building purposes. Illegal capture of the turtles is also widespread.

HAWKSBILL TURTLE DATA PANEL Hawksbill turtle Eretmochelys imbricata

• Family: Cheloniidae
• World population: Unknown
• Distribution: Atlantic, Pacific, and Indian Oceans
• Habitat: Shallow tropical and subtropical seas; coral reefs; mangrove bays; estuaries
• Size: Length: female 24-37 in (62-94 cm); male up to 39 in (99 cm)
• Form: Oval shell with serrated (toothed) edge; dark pattern on amber background
• Diet: Sponges and mollusks; algae
• Breeding: Up to 140 eggs per clutch; 4-5 clutches per season
• Related endangered species: All other sea turtles

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