Bivalves even make their own shells. An internal organ called the mantle secretes calcium carbonate so that as the inner invertebrate grows, the outer shell provides a roomier home.
Many bivalve species play important roles in aquatic and marine ecosystems by filtering the water and serving as habitat and prey for a variety of sea life.
This diverse group of species, estimated at about 9,, inhabits virtually the entire world ocean, from the balmy tropics to the sub-zero Arctic, and from the deep ocean to sandy and rocky shorelines. A few have even taken up residence around hydrothermal vents found deep in the Pacific Ocean, below 13, feet. Home Ocean Facts What is a bivalve mollusk? The shell of the calf cowrie is not quite as attractive as that of other members of this group.
This shell is usually brown and white with spots. Because of the lack of color, the calf cowrie shell does not fetch as high a price on the shell collector market. The muted colors provide this animal with a good means of camouflage.
Limpets are related to snails, and closely resemble them with a few exceptions. Their shell is cone shaped and has a small hole on the tip. Limpets feed on algae and detritus, and then expel waste materials through the hole on top.
Because of this, they look like tiny volcanoes as they roam around the rocks. Chitons are small mollusks that are common in the Caribbean. They are nocturnal and move around the rocks at night feeding on algae. Their strange appearance is reminiscent of the ancient trilobites of prehistoric times. They are commonly introduced into the home aquarium with live rock. The octopus is probably one of the most well known mollusks.
They have lost their hard shell, and have evolved large, complex brains to compensate. The octopus swims by jet propulsion by siphoning water through its body. When threatened, it can release a blinding cloud of black ink. They feed on crustaceans and fish.
The blue ring octopus is a small species found in the waters of Australia. With its bright blue markings it is a beautiful creature, but it is also quite deadly. Although it is only about eight inches in diameter with its tentacles spread, its bite is poisonous enough to kill a person. The blue ring is the only poisonous octopus species known to exist.
The squid is another member of the mollusk family that has lost its hard shell. Like the octopus, squid have suction cups on their arms that aid in capturing their prey. They feed on fish and crustaceans. This common squid species is found throughout the Atlantic United States coast and grows to a length of 5 inches. Cuttlefish are very closely related to squid.
One noticeable difference is that the cuttlefish has noticeably shorter tentacles. These animals also have specialized tentacles that can shoot out quickly to catch their prey. Cuttlefish are masters of disguise. They can change colors in an instant, and have actually been observed to use flashing colors as a means of communication. For many years the nautilus was thought to be a rare deep water species, but recently they have been discovered in large numbers on Indo-Pacific coral reefs.
They are nocturnal animals, swimming around the reef at night in search of small fish and shrimp. Their unique shells are highly prized by shell collectors. To search this site, type your search word s in the box below and click the search button:. All rights reserved. Content from this Website may not be used in any form without written permission from the site owner.
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Marine Mammals. Mollusks Mollusks comprise a group of soft-bodied animals that includes snails , clams , and sea slugs. Yellow Nudibranch Notodoris minor The nudibranch is without a doubt the most colorful of all the mollusks.
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