Bivalvia

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by anh2135092
Last updated 6 years ago

Discipline:
Science
Subject:
Zoology
Grade:
12

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Bivalvia

Some are small, spherical/oval shells with equal left and right valves or laterally compressed shells, which allows more rapid movement through sediments. Burrowers move up and down through mud and sand by extending their large foot, burying into the sediment of the ocean floor. Others can 'swim' through the water by clapping their valves together. They have sensory tentacles and photoreceptors. They are able to extend a long siphon up to the surface to suck water in for filtering and breathing.

Human Connection? Many bivalves like clams, oysters, and mussels are used as food in places all over the world. Pearl oysters are used for commercial production of pearls. They can also cause economic damage. The larvae of some freshwater mussels can be serious parasites of fish, and others bore through wood damaging wooden ships, pilings, and other wood structures.

Class Bivalvia of Phylum Mollusca(bi-valve-ee-a)> Mollusks with shells made of two pieces known as valves.> The valves are symmetrical left and right and usually the same size.> Two large muscles called adductors hold and close the valves together.> Over 15,000 species of clams, oysters, mussels, and scallops.> Can range anywhere from 0.01 in. to 4 ft.

Bivalves usually require both males and females to reproduce. Some either have the organs of both sexes or start out as males and later become females. Bivalve eggs and sperm are usually released into the water, where fertilization takes place. The eggs hatch into veligers and feed on plankton until they settle on rocks, wood or the ocean bottom to begin developing their valves.

Most bivalves are marine and occur at all depths on many different substratesIn shallow seas, bivalves are usually dominant on rocky and sandy costsThey also occur the deepest zones of the ocean such as the abyssal and hadal zoneNone are terrestrial (living on land) but some high-intertidal and freshwater species can endure drought conditions

Most bivalves are filter feeders, detritivores (consumer of loose organic material) but some are scavengers or even predators. The four main feeding types of bivalves are defined by gill structure: protobranchs, filibranchs, lamellibranchs, and septibranchs. These gills have adapted as filtering devices called ctenidia. Bivalvia are the only mollusks characterized by the absence of a radula (comparable to tongue).

Bivalvia

Bivalves are closely related to gastropods including snails, slugs, limpets, and sea hares. Gastropods are one of the most diverse groups of animals, both in form, habit, and habitat. They are the largest group of mollusks, with more than 62,000 living species. They compromise 80% of living mollusks.

The greatest affinity of bivalves is with coral reefs. One group of bivalves have highly intimate relationship with other marine invertebrates, particularly on soft shores and coral reefs. They form an association where there is no detriment to the host and still get protection, food, and respiratory currents. On soft shores, they share food and sometimes attaching to the body of the host. Many bivalves act as an important food source for gastropods, fish, and shore birds.


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