The Class Cephalopoda

The Class Cephalopoda - squids have a shell that is reduced...

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The Class Cephalopoda The class Cephalopoda (literally "head-footed") includes squids, cuttlefish, octopuses, and nautiluses (and extinct relatives, the goniatites, ammonoids, and ammonites). The presence of a shell in many representatives of this class has yielded an impressive fossil record. Squids and octopuses can squeeze water from their mantle cavity out through a funnel (shown in Figure 9), thus propelling them with a form of jet propulsion. Surrounding their head are tentacles with suckers that can grasp prey and deliver it to a powerful beak/mouth. Cephalopods in general have well-developed sense organs, including focusing camera-type eyes. Most cephalopods, especially octopuses, have well- developed brains and show a capacity for learning. Nautiluses are enclosed in shells,
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Unformatted text preview: squids have a shell that is reduced and internal, while octopuses lack a shell. Squids and octopuses possess ink sacs from which they squirt a cloud of ink, as a means of escaping predators. Squids possess a vestigial skeleton under the mantle, called the pen, which surrounds the visceral mass. A squid has three hearts, one pumps blood to internal organs; two pump blood to the gills in the mantle cavity. Gonads make up a large portion of the visceral mass. Cephalopds have separate sexes. Spermatophores contain sperm, which the male passes to the female mantle cavity by way of one of his tentacles. After fertilization, eggs are attached to the substratum in strings containing up to 100 eggs....
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This note was uploaded on 11/29/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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The Class Cephalopoda - squids have a shell that is reduced...

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