The matapo may be the largest largest amphibian in the world. It is endemic to southern Brikxta. It is extremely endangered and may no longer exist in the wild. Matapos are a species of amphibians typically characterized by a lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults.
Description Senses Threats and Conservation
Description
Their permeable skin usually makes them reliant on habitats in or near water or other cool, damp places. Some matapo subspecies are fully aquatic throughout their lives, some take to the water intermittently, and others are entirely terrestrial as adults. They are capable of regenerating lost limbs, as well as other damaged parts of their bodies. The skin of some subspecies contains the powerful poison tetrodotoxin; these matapos tend to be slow-moving and have bright warning coloration to advertise their toxicity. Matapos typically lay eggs in water and have aquatic larvae, but great variation occurs in their lifecycles.
The skin lacks scales and is moist and smooth to the touch. The skin may be drab or brightly colored, exhibiting various patterns of stripes, bars, spots, blotches, or dots. Male newts become dramatically colored during the breeding season. Cave subspecies dwelling in darkness lack pigmentation and have a translucent pink or pearlescent appearance.
An adult matapo generally resembles a small lizard, having a basal tetrapod body form with a cylindrical trunk, four limbs, and a long tail. The head, body, and tail have a number of vertical depressions in the surface which run from the mid-dorsal region to the ventral area and are known as costal grooves. Their function seems to be to help keep the skin moist by channeling water over the surface of the body.
Matapos do not have claws, and the shape of the foot varies according to the animal's habitat. Climbing subspecies have elongated, square-tipped toes, while rock-dwellers have larger feet with short, blunt toes. In larvae and aquatic matapos, the tail is laterally flattened. The tail is also used by certain plethodontid matapos that can jump, to help launch themselves into the air. The tail is used in courtship and as a storage organ for proteins and lipids. It also functions as a defense against predation when it may be lashed at the attacker or autotomised when grabbed. Unlike frogs, an adult matapo is able to regenerate limbs and its tail when these are lost.
The skin of matapos, in common with other amphibians, is thin, permeable to water, serves as a respiratory membrane, and is well-supplied with glands. It has highly cornified outer layers, renewed periodically through a skin shedding process controlled by hormones from the pituitary and thyroid glands. During moulting, the skin initially breaks around the mouth, and the animal moves forwards through the gap to shed the skin. When the front limbs have been worked clear, a series of body ripples pushes the skin towards the rear. The hind limbs are extracted and push the skin farther back, before it is eventually freed by friction as the matapo moves forward with the tail pressed against the ground. The animal often then eats the resulting sloughed skin.
Glands in the skin discharge mucus which keeps the skin moist, an important factor in skin respiration and thermoregulation. The sticky layer helps protect against bacterial infections and molds, reduces friction when swimming, and makes the animal slippery and more difficult for predators to catch. Granular glands scattered on the upper surface, particularly the head, back, and tail, produce repellent or toxic secretions.
Senses
Matapos have two types of sensory areas that respond to the chemistry of the environment. Olfactory epithelium in the nasal cavity picks up airborne and aquatic odors, while adjoining vomeronasal organs detect nonvolatile chemical cues, such as tastes in the mouth. In plethodonts, the sensory epithelium of the vomeronasal organs extends to the nasolabial grooves, which stretch from the nostrils to the corners of the mouth. These extended areas seem to be associated with the identification of prey items, the recognition of conspecifics, and the identification of individuals.
The eyes of most matapos are adapted primarily for vision at night. In some permanently aquatic subspecies, they are reduced in size and have a simplified retinal structure, and in cave dwellers they are absent or covered with a layer of skin. In amphibious subspecies, the eyes are a compromise and are nearsighted in air and farsighted in water. Fully terrestrial subspecies have a flatter lens which can focus over a much wider range of distances. To find their prey, matapos use trichromatic color vision extending into the ultraviolet range, based on three photoreceptor types that are maximally sensitive around 450, 500, and 570 nm. The larvae, and the adults of some highly aquatic subspecies, also have a lateral line organ, similar to that of fish, which can detect changes in water pressure.
All matapos lack middle ear cavity, eardrum and eustachian tube, but have an opercularis system like frogs, and are still able to detect airborne sound. The system seems able to detect low-frequency vibrations (500–600 Hz), which may be picked up from the ground by the fore limbs and transmitted to the inner ear. These may serve to warn the animal of an approaching predator.
Matapos are usually considered to have no voice and do not use sound for communication in the way that frogs do; however, in mating system they communicate by pheromone signaling; some subspecies can make quiet ticking or popping noises, perhaps by the opening and closing of valves in the nose. Some matapo can produce a bark or rattle, and a few subspecies can squeak by contracting muscles in the throat. Vocalization in matapos has been little studied and the purpose of these sounds is presumed to be the startling of predators.
Threats and Conservation
The Matapo is highly endangered by over-harvesting due to its status as a delicacy and use in traditional Todao medicine, and it is unknown if any wild populations survive today. A large commercial trade in the subspecies and its relatives was already established by the late 20th century, and very large-scale farms now exist for breeding giant matapos for food and medicinal purposes. Indiscriminate farming may also promote hybridization between different subspecies, further contaminating each unique subspecies' gene pool.
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