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The evolution of the molluscs is the way in which the Mollusca, one of the largest groups of invertebrate animals, evolved. This phylum includes gastropods , bivalves , scaphopods , cephalopods , and several other groups.
Mollusca is a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks [a] (/ ˈ m ɒ l ə s k s /). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda . [ 5 ]
The first ammonite mollusks appeared. Trilobites, the mollusk-like brachiopods and the great coral reefs, were still common. The Late Devonian extinction occurred at the beginning of the last phase of the Devonian period, the Famennian faunal stage, (the Frasnian-Famennian boundary), about 372.15 Ma.
By Will Dunham. WASHINGTON (Reuters) - Earth's roughly 76,000 species of mollusks come in an impressive variety of forms including clams, oysters, scallops, mussels, snails, slugs and even some ...
Already long assumed to be a paraphyletic assemblage leading to more derived gnathostomes, the discovery of Entelognathus suggests that placoderms are directly ancestral to modern bony fish. As in most vertebrates , fish jaws are bony or cartilaginous and oppose vertically, comprising an upper jaw and a lower jaw .
Conch are species of sea snail in the phylum Mollusca. Their shells consist of about 95% calcium carbonate and 5% organic matter. Conch are harvested for their edible meat and decorative shell. The shells are often used for decoration and as a musical instrument. [6] [7]
A slug on a wall in Kanagawa, Japan.. Slug, or land slug, is a common name for any apparently shell-less terrestrial gastropod mollusc.The word slug is also often used as part of the common name of any gastropod mollusc that has no shell, a very reduced shell, or only a small internal shell, particularly sea slugs and semi-slugs (this is in contrast to the common name snail, which applies to ...
Malacology [a] is the branch of invertebrate zoology that deals with the study of the Mollusca (molluscs or mollusks), the second-largest phylum of animals in terms of described species [1] after the arthropods. Mollusks include snails and slugs, clams, and cephalopods, along with numerous other kinds, many of which have shells.