Friday, 25 November 2011

Animals with No Legs

There are many animals with no legs. So they can be grouped together.

Snake




Snail




Fish




Seal



Whale



4 comments:

  1. This is highly inaccurate given the placements of such animals in phylogeny. The snail is not a vertebrate chordate but is a gastropod in the phylum Mollusca, along with the cephalopods (octopus, squids, and cuttlefish) and the bivalves (clams, oysters, mussels). The fish is a true vertebrate chordate and are not a monophyletic group: different fish are merely aquatic non-tetrapod vertebrates. The remaining animals on this list are all tetrapods, vertebrates with four limbs, but many species have secondarily lost their limbs over the course of evolution. The snake is a diapsid reptile of the order Squamata, among which the pattern of limblessness has evolved independently multiple times in the fossil record. The seal and the whale are both eutherian mammalian synapsids. The whale is a highly derived relative of the Artiodactyla ungulates, while the seal is a member of the caniformia subdivision of the order Carnivora (along with dogs and bears). The whale and the seal are not truly limbless as the seal possesses all four limbs but are morphologically adapted for underwater propulsion and not for cursorial terrestrial locomotion, forcing the seal to ambulate via a rhythmic undulation on land. The whale retains its pectoral girdle and forelimbs but its pelvis and rear limbs have become vestigal, with its tail (lost in the seal) serving to propel it in the water. In final summary the list of animals with no legs is not a taxonomically valid arrangement, as the lack of functional limbs for locomotory purposes may be found in groups that never developed appendages of such structure or in clades that have secondarily lost them independently of other lineages that have evolved convergently to have a similar anatomical structure.

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