Search results
Results from the WOW.Com Content Network
Amphibians have soft bodies with thin skins, and lack claws, defensive armour, or spines. Nevertheless, they have evolved various defence mechanisms to keep themselves alive. The first line of defence in salamanders and frogs is the mucous secretion that they produce. This keeps their skin moist and makes them slippery and difficult to grip.
One example of asymmetric invertebrates includes all gastropod species. This is easily seen in snails and sea snails , which have helical shells. Slugs appear externally symmetrical, but their pneumostome (breathing hole) is located on the right side.
A craniate is a member of the Craniata (sometimes called the Craniota), a proposed clade of chordate animals with a skull of hard bone or cartilage.Living representatives are the Myxini (hagfishes), Hyperoartia (including lampreys), and the much more numerous Gnathostomata (jawed vertebrates).
Class Amphibia (amphibians, some ancestral to the amniotes)—now a paraphyletic group; Class Synapsida (mammals and their extinct relatives) Class Sauropsida (reptiles and birds) While this traditional taxonomy is orderly, most of the groups are paraphyletic, meaning that the structure does not accurately reflect the natural evolved grouping. [47]
Many vertebrates are limbless, limb-reduced, or apodous, with a body plan consisting of a head and vertebral column, but no adjoining limbs such as legs or fins. Jawless fish are limbless but may have preceded the evolution of vertebrate limbs, whereas numerous reptile and amphibian lineages – and some eels and eel-like fish – independently lost their limbs.
In the 10th edition of Systema Naturae, Carl Linnaeus described the Amphibia as: [1]. Animals that are distinguished by a body cold and generally naked; stern and expressive countenance; harsh voice; mostly lurid color; filthy odor; a few are furnished with a horrid poison; all have cartilaginous bones, slow circulation, exquisite sight and hearing, large pulmonary vessels, lobate liver ...
Hatching takes place after 10 days of gestation; the young echidna, called a puggle, [23] [24] born larval and fetus-like, then sucks milk from the pores of the two milk patches (monotremes have no teats) and remains in the pouch for 45 to 55 days, [25] at which time it starts to develop spines. The mother digs a nursery burrow and deposits the ...
Found in the Philippines, they have an average length of 12.5 mm (0.49 in), and are threatened by overfishing. [55] Whale shark: The largest fish is the whale shark. It is a slow-moving, filter-feeding shark with a maximum published length of 20 m (66 ft) and a maximum weight of 34 tonnes (33 long tons; 37 short tons).