Evolution and systematics

The earliest unequivocal record of the order Neritopsina is Late Sularian-Devonian (428-374 million years ago). Earlier Ordovician records are based on protoconch and adult shell similarities. The Neritopsina were noted as being very distinct from other archaeogastropods in the early twentieth century, but only since the 1970s has that placement been broadly accepted. Neritopsina coil their shells differently than other coiled gastropods and therefore lack a central shell axis, the columella,...

What is a protostome

The term Protostomia (from the Greek proto, meaning first, and stoma, meaning mouth) was coined by the biologist Karl Grobben in 1908. It distinguishes a group of invertebrate animals based upon the fate of the blastopore (the first opening of the early digestive tract) during embryonic development. Animals in which the blastopore becomes the mouth are called protostomes those in which the mouth develops after the anus are called deuterostomes (from the Greek deutero, meaning second, and stoma,...

Significance to humans

Many kinds of bivalves, especially clams, cockles, mussels, oysters, and scallops, have served as important food sources for fish, vertebrates, other invertebrates, and humans. Aboriginal populations of many cultures have left evidence of eating bivalves in their kitchen middens (mounds or deposits of refuse from meals). Recent practices rely both on harvesting wild populations and on aquaculture in either open or closed aquatic systems. Members of the marine Pteriidae and freshwater Unionoidea...

Resources

How Many Arachnida and Myriapoda Are There Worldwide and in Amazonia In Encyclopedia of Biodiversity. New York Academic Press, 2000. Beacham, Walton, Frank V. Castronova, and Suzanne Sessine, eds. Beacham's Guide to the Endangered Species of North America. Detroit, MI Gale Group, 2001. Bosik, J. J. Common Names of Insects and Related Organisms. Lanham, MD Entomological Society of America, 1997. Cloudsley-Thompson, J. L. Spiders, Scorpions, Centipedes and Mites....

Millipedes

Photo A millipede (Sigmoria aberrans) displaying warning colors. (Photo by Gilbert S. Grant Photo Researchers, Inc. Reproduced by permission.) The class Diplopoda contains about 10,000 described species in 15 orders and 148 families. Scientists believe that as many as 70,000 additional species have yet to be identified. The millipedes were once classified as a subclass of the class Myriapoda, which also contained the centipedes (now assigned to class Chilopoda). Since then, all four major...

Ovotestis Posterior hermaphrodite duct

Sea slug anatomy. (Illustration by Christina St. Clair) short periods of time as well. Benthic sea slugs are slow-moving organisms. They live relatively sedentary lives, and some species spend their entire life on one prey organism such as a sponge or coral reef. Almost all dispersal to new areas occurs during the veliger larval stage veligers will settle out of the water column only when suitable substrate is present. Some larvae have crossed entire ocean basins because of lack of suitable...

Reproductive Biology

CONSERVATION STATUS Not listed by the IUCN. SIGNIFICANCE TO HUMANS None known. Barnes, Robert D. Invertebrate Zoology. 4th ed. Philadelphia Saunders College Publishing, 1980. Beesley, Pamela L., Graham J. B. Ross, and Alice Wells. Mollusca The Southern Synthesis, Part A. Canberra Australian Biological Resources Study, 1998. Geise, Arthur C., and John S. Pearse. Reproduction of Marine Invertebrates. Vol. V, Mollusks Pelecypods and Lesser Classes. London Academic Press, 1975. Purchon, R. D. The...

Feeding Ecology And Diet

It is a filter-feeding worm, dining on suspended organic material. Sea water is pumped through the tube by winglike notopo-dia, which secrete mucus that is drawn back, forming a bag. Blake, James A., B. Hilbig, and P. H. Scott. The Annelida Part 2 Polychaeta Phyllodocida (Syllidae and Scale-bearing families), Amphinomida and Eunicida. Taxonomic Atlas of the Benthic Fauna of the Santa Maria Basin and the Western Santa Barbara Channel series, Vol. 5. Santa Barbara, CA Santa Barbara Museum of...

Lungbearing snails and slugs

Number of families Approximately 120 Mainly terrestrial but also freshwater and marine slugs and snails, almost all having an enclosed lung Photo A garden snail (Helix aspersa) issuing defensive foam. (Photo by Holt Studios, Int. Photo Researchers, Inc. Reproduced by permission.) The earliest fossil pulmonate land snails date back over 300 million years to the Carboniferous period of North America and Europe, although there is some controversy as to whether these belong to primitive pulmonate...

Behavior

The large number and sheer diversity of protostomes necessitates a restriction on the kinds of behaviors (and species) that can be discussed in this chapter. The behaviors highlighted here are based in part on their importance to the survival of an individual organism. Protostomes are some of the most morphologically complex, ecologically diverse, and behaviorally versatile organisms in the animal kingdom. They consist of more than one million species divided into approximately 20 phyla. Major...

Clam sand and tubeworms

Hediste Diversicolor

Phylum Annelida Class Polychaeta Number of families 86 Segmented worms with numerous bristles and one pair of parapodia per segment Photo Bristle or fire worms (Chloeia sp.) primarily come out at night and are scavangers. (Photo Tony Wu www.silent-symphony.com. Reproduced by permission.) Phylum Annelida Class Polychaeta Number of families 86 Segmented worms with numerous bristles and one pair of parapodia per segment Photo Bristle or fire worms (Chloeia sp.) primarily come out at night and are...

Nautilids octopods cuttlefishes squids and relatives

Mollusks bearing a radula (toothed tongue) and well-developed heads mouth characterized by a dorsoventral pair of horny jaws known as beaks and encircled by the bases of 8-ca. 60 grasping appendages single pair of lateral, image-forming eyes well-developed brain and peripheral nervous system Photo A greater blue ringed octopus (Hapalo-chlaena lunulata) takes a crab as it emerges from its hole. (Photo Tony Wu www.silent-symphony .com. Reproduced by permission.)

Chitons

Phylum Mollusca Class Polyplacophora Number of families 10 Mollusks with a flattened, ovoid shape, broad ventral foot, and eight (sometimes seven) dorsal shell plates that overlap one another and allow the animal to bend and mold itself onto a rock to avoid wave dislodgement Photo The lined chiton (Tonicella lineata) is a slow moving mollusk with a shell composed of multiple plates. (Photo by David Hall Photo Researchers, Inc. Reproduced by permission.) The earliest fossil chitons occur in the...