MOLLUSKS - CRUSTASCEANS -...

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Vintage-Views Antique Prints and Maps :: Antique Prints :: Natural History :: Mollusca :: MOLLUSKS - CRUSTASCEANS - ECHINODERMS, HISTORICAL CONCHOLOGY,MALACOLOGY PRINT,1894 Original Antique Wood Engraving

MOLLUSKS - CRUSTASCEANS - ECHINODERMS, HISTORICAL CONCHOLOGY,MALACOLOGY PRINT,1894 Original Antique Wood Engraving

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The mollusks or molluscs are the large and diverse phylum Mollusca, which includes a variety of familiar animals well-known for their decorative shells or as seafood. These range from tiny snails, clams, and abalone to squid, cuttlefish and the octopus (which is considered the most intelligent invertebrate). There are some 112,000 species within this phylum.The giant squid, which until recently had not been observed alive in its adult form, is the largest invertebrate; although it is possible that the colossal squid is even larger. The scientific study of mollusks is called malacology.Mollusks are triploblastic protostomes. The principal body cavity is a blood-filled hemocoel. They have a true coelom (eucoelom); any coelomic cavities have been reduced to vestiges around the hearts, gonads, and metanephridia (kidney-like organs). The body is often divided into a head, with eyes or tentacles, a muscular foot and a visceral mass housing the organs. Mollusks have a mantle, which is a fold of the outer skin lining the shell, and a muscular foot that is used for motion. Many mollusks have their mantle produce a calcium carbonate external shell and their gill extracts oxygen from the water and disposes waste. All species of the phylum Mollusca have a complete digestive tract that starts from the mouth to the anus. Many have a feeding structure, the radula, mostly composed of chitin. Radulae are diverse within the Mollusca, ranging from structures used to scrape algae off rocks, to the harpoon-like structures of cone snails. Cephalopods (squid, octopodes, cuttlefish) also possess a chitinous beak. Unlike the closely related annelids, mollusks lack body segmentation. Development passes through one or two trochophore stages, one of which (the veliger) is unique to the group. These suggest a close relationship between the mollusks and various other protostomes, notably the Annelids. Mollusk fossils are some of the best known and are found from the Cambrian onwards. The oldest fossil seems to be Odontogriphus omalus, found in the Burgess Shale. It lived about 500 millions years ago. The crustaceans (Crustacea) are a large group of arthropods (55,000 species), usually treated as a subphylum . They include various familiar animals, such as lobsters, crabs, shrimp and barnacles. The majority are aquatic, living in either fresh water or marine environments, but a few groups have adapted to terrestrial life, such as terrestrial crabs, terrestrial hermit crabs and woodlice. The majority are motile, moving about independently, although a few taxa are parasitic and live attached to their hosts (including sea lice, fish lice, whale lice, tongue worms, and Cymothoa exigua), and adult barnacles live a sessile life - they are attached head-first to the substrate and cannot move independently. The scientific study of crustaceans is known as carcinology. Other names for carcinology are malacostracology, crustaceology and crustalogy, and a scientist who works in carcinology is a carcinologist, crustaceologist or crustalogist. Echinoderms (Phylum Echinodermata, from the Greek for spiny skin) are a phylum of marine animals found at all depths. This phylum appeared in the early Cambrian Period and contains about 7,000 living species and 13,000 extinct ones. Five or six classes (six counting Concentricycloidea) are alive today: * Asteroidea (asteroids, starfish, or sea stars): about 1,500 species that capture prey for their own food. * Concentricycloidea (sea daisies), notable for their unique water vascular system; two species; recently merged into Asteroidea. * Crinoidea (crinoids, feather stars or sea lilies): about 600 species that are suspension feeders. * Echinoidea (echinoids, sea urchins and sand dollars): notable for their movable spines; about 1,000 species. * Holothuroidea (sea cucumbers): elongated animals resembling slugs; about 1,000 species. * Ophiuroidea (brittle stars and basket stars), the physically largest of echinoderms; about 1,500 species. Extinct forms known from fossils include blastoids, edrioasteroids, and several early Cambrian animals such as Helicoplacus, carpoids, Homalozoa, and possibly machaerids. Echinodermata is the largest animal phylum to lack any freshwater or terrestrial representatives.

Published for Joseph Meyer Meyers Konversations

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SKU	0527827k6
Quantity in stock	1 item(s) available
Price:	US$20.00

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