BIOL 1000 Lecture Notes - Lecture 7: Crassostrea, Cephalopod, Loligo
Document Summary
Genus octopus: eight tentacles with adhesive suckers, more sedentary than squids, bottom dwelling crawlers; globular bodies, lacking fins, territorial, living in dens. Genus nautilus: primitive in structure, external, chambered shell in which gas is secreted to change buoyancy, head bears many tentacles which lack suckers. Squid, octopus, nautilus, cuttlefish and extinct ammonites: largest invertebrates, tentacles/arms, swim using jet propulsion associated with the mantle cavity, well developed cephalization including simple eyes which are extremely light sensitive but do not see colour. Genus pecten (scallops: swim, reduced foot, well developed single adductor muscle for opening and closing valves (what is eaten, mantle margin possesses sensory tentacles and ocelli (light sensitive eyes) Class bivalvia chlamys iceland scallop shell. Genus crassostrea (oyster: attached by secreted cement", two valves unequal in size, pearls produced by nacreous layer of shell secreted around sand grains or parasites, entire body eaten.
