Assignment 25- Andy

Cephalopods are some of the most interesting organisms in the world. They fall into class Cephalopodia in phylum mollusca of the Kingdom Animala and are invertebrates. Some of the most well known creatures in this class include octopuses, squids, cuttlefish, and the chambered nautilus. The animals in this class all have eight arms. These are used to propel the organism and grasp surfaces and prey. Squid have two extra, longer tentacles that they use to feel and attack prey. The visceral mass of cephalopods is contained within the mantle, or the head, of the organism. The mantle siphons water through the body to propel the organism forward. Cephalopods are the only mollusks with closed circulatory systems. They possess two brachial hearts that pump hemolymph (blood-like fluid) through the capillaries of the gills. A single heart then pumps the blood throughout the body. Instead of using hemoglobin (iron-based) to carry oxygen cephalopods use hemocyanin (copper-based) to carry oxygen throughout the body.