Mollusk-Three-Fold


 * __ PHYLUM: MOLLUSCA __**

By: Ashley Hanooman Mariya Bogorodova Siu Lam Koo Amanda Surujdeo

Periods 3-4 GroupB
 * PHYLUM MOLLUSCA**

There are around 85,000 recognized extant species in phylum Mollusca, making it the largest marine phylum as it contains about 23% of named marine organisms. However representatives live in marine as well as freshwater and terrestrial habitats. Molluscs are highly diverse in size, anatomical structure, behavior and habitat.

à Class Bilvalvia: Bay Scallops

Bay scallop is a marine bivalve mollusk of the family Pectinidae. Scallops are very abundant and are found in every world’s ocean. Scallops are the only migratory bivalve and have a strongly developed adductor muscle. Their shells may seem regular to a biologist but to a shell collector such findings would be priceless since the shells are very beautiful. Most scallops eat planktons. Scallops usually swim freely around but sometimes they dig themselves into sand. Scallops are either males, females, or protoandrous hermaphrodites (males when young then switching to female). Red roe is that of a female, and white, that of a male. Spermatozoa and ova are released freely into the water during mating season and fertilized ova sink to the bottom. After several weeks, the immature scallop hatches and the larvae drift in the plankton until settling to the bottom again to grow, usually attaching by means of byssal threads.

à Class Gastropoda: Periwinkle Snails

Periwinkles are small marine snails. Periwinkles are widely distributed shore (littoral) snails, chiefly herbivorous, usually found on rocks, stones, or pilings between high- and low-tide marks; a few are found on mud flats, and some tropical forms are found on the prop roots or mangrove trees. Periwinkles are important as a favorite food of many shore birds, particularly ducks.

à Class Gastropoda: Sea slugs/ Headshield slugs

Sea slugs are members of class Gastropoda and clade Heterobranchia. There are many different kinds of slugs but we are going to be focusing on headshield slugs. They live just beneath the surface of the sand and can also be seen crawling on rocks. Many sea slugs, including headshield slugs, are brightly colored and therefore easy to spot. Headshiel slugs have a well-developed headshield, a characteristic broadening at the head, which is used to plow beneath the surface of the sand. This headshield prevents the sand entering the mantle cavity, an evolutionary advantage.

à Class Cephalopoda: Octopus

The octopus belongs to class Cephalopoda and it is probably the most intelligent invertebrate; considering that 95% of animals are invertebrates this is a remarkable quality. The octopus inhabits many diverse regions of the ocean, especially coral reefs. For defense against predators, they hide, flee quickly, expel ink, or use color-changing camouflage .All octopuses are poisonous but only the blue ringed octopus has venom strong enough to kill humans. In fact, octopuses rarely use their venom unless provoked, when attacked they generally splash ink into the predators face and escape. An octopus has a highly complex nervous system, only part of which is localized in its brain. Such nervous system may explain their complex movements and unique learning skills. Octopuses are preyed upon by sharks, dolphins, morays and conger eels.

à Class Cephalopoda: Giant Squid

Giant Squid is giant. It can grow as big as 13 feet, specimens as long as 20 feet had been reported but it has not been recorded scientifically. The only predator of these majestic creatures is the sperm whale. Giant squid are very widespread, occurring in all of the world's oceans. They are usually found near continental and island slopes from the North Atlantic Ocean.

à Class Polyplacophora : Lined Chiton/T. lineata

Lined Chiton is a very colorful chiton, having blue, purple or black straight or zig-zag lines on each of the eight valves. The background color of the valves is often brown or red, but can also be bright blue or yellow to orange. The girdle is hairless and brown to red or pink, often with regular yellow or white patches. This species grows to 5 cm in length. The natural range of //T. lineata// stretches from the Aluetian Islands of Alaska to San Miguel Island of California, as well as the Sea of Okhotsk of Russia and northern Japan.


 * FUN FACTS**

· Giant squid is the largest invertebrate on Earth. The length of a giant squid is 60 feet long. It weighs around 900 kgs. Octopus is the smartest invertebrate · Octopuses have three [|hearts]. Two pump blood through each of the two [|gills], while the third pumps blood through the body. · A group of giant squids is known as a school. · The blue ringed octopus is among one of the most popular aquarium animals, it’s ironic because it’s also one of the most poisonous animals on earth. · Octopuses have blue blood · The smallest octopus is the Californian octopus, reaching 1 inch. · Octopuses have a short life span, from 6 months to a few years. · The Giant Octopus is the biggest octopus, reaching 30 feet and 400 pounds. · The smallest octopus is the Californian octopus, reaching 1 inch · Mollusca is the largest marine phylum


 * Bibliography**
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