Biology summary of one cephalopod, one bivalve and one chiton of your choosing - Essay Example

ales use the hectocotylus (a special arm) to dispense packets of sperm (spermatophores) from the reproductive tract’s terminal organ/ cephalopod penis, into the mantle cavity of the females. In benthic octopuses, it is the third arm on the right that serves as the hectocolylus. A few months following this mating process, the males die, and in some octopus species, females have the conditions to keep viable sperms within their bodies until their eggs reach maturity. After fertilization of the eggs, the female lays approximately 200,000 eggs, but such numbers vary depending on the kind of species, genera, families, and the individual octopus.

While open octopuses mainly feed on fish, other cephalopods and prawns, the bottom dwellers, on the other hand, feed mainly on clams, whelks, polychaete worms and crabs. Using paralyzing saliva, octopuses inject their prey and break down their bodies using their beaks. As for shelled molluscs, an octopus feeds on them by drilling a hole through their shells, inject their degrading saliva into the hole and extract the inner soft tissues (Campbell & Reece, 2005, p. 86). Octopuses can live in various parts of the ocean such as the ocean floor, pelagic waters and on coral reefs.

These organisms have a keen eye sight (that can recognize light polarizations), a good sense of touch and statocysts that detect sound. Octopuses have no internal or external skeletons to enable them squeeze through tight spaces, are intelligent, fast and can mimic shapes of other creatures when hunting for food and are able to avoid predation due to their speed, ability to camouflage, presence of venom and expulsion of ink (Campbell & Reece, 2005, p. 90). An example of a bivalve is a scallop.

Scallops belong to the kingdom animalia, phylum millusca, class bivalvia, order ostreoida, sub-orders pectinoida and pectinina, superfamily pectinoidea and family pectinidae. Scallops are bilaterally symmetrical with the scallop composed of two valves/ halves; the