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Group 3: Mollusks


Group 3 - Shells: Phylum Mollusca is a diverse phylum that includes many well-known ocean invertebrates. Mollusca is the second largest animal phylum and the largest marine animal phylum. Mollusks make up about 23% of known marine life.

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5 Fun Facts - Mollusks

Fun facts Marine Mollusks

Marine mollusks are divided into several different classes. The three main classes are Gastropoda, Bivalvia and Cephalopoda. Gastropoda is the largest and most varied class of mollusks. Sea snails, nudibranchs, abalones and limpets are all marine gastropods. Bivalvia includes clams, mussels, scallop and oysters. Cephalopoda is a class of exclusively marine animals, including octopus, squid, cuttlefish and nautilus.

Identification: There are three common features that are used to distinguish mollusks from animals in other phyla. All mollusks have a muscular foot, which varies in shape and use depending on the species.

Muscular Foot: In gastropods, the foot is on the bottom of the animal allowing the animal to suction onto hard surfaces. The foot of bivalves allows the animal to burrow into sand and sediment. The foot of cephalopods has evolved into arms or tentacles.

Arm or tentacle: The terms "arm" and "tentacle" are used interchangeably when describing cephalopods, but they can be distinguished by by the location of their suckers. The suckers on the arms run the entire length of the limb. On tentacles, the suckers are only located near the end of the limb.

Mantle: Mollusks also have a mantle, a soft, muscular structure forming the outer wall of the body protecting the internal organs and aid in respiration, excretion and sensory perception. In most mollusks species, outermost layer of the mantle will harden to create a protective shell. Or they can develop internally such as the cuttlebone of a cuttlefish.

Radulae: Finally many mollusks have radulae, bands of tiny teeth used for scraping and tearing food as it enters the mouth. Some gastropods are carnivores while others are herbivores. The radulae are generally adapted to the diet of a particular species.

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