Cephalopod Anatomy

Organs:

·         High brain-to-body mass ratio; most intelligent of the invertebrates.

·         Three hearts.

·         Gills and Siphon for breathing and jet-propulsion respectively.

·         Gonads typically at the top of the mantle (head).

·         Most have ink sacs.

·         Have bird-like beaks, and most have radulas (multiple rows of up to nine teeth).

·         Large, highly developed eyes, yet they are colorblind.

Appendages

·         Most have at least eight arms and two or more tentacles.

·         Arms are lined with suction cups and tentacles usually have the suckers only at the tips.

·         “Cephalopod” means “head-foot.”

Size and Color

·         As big as 60 feet (Giant Squid) to as little as half an inch (Pygmy Squid).

·         Most have chromatophores which stretch and squash to change color.

Nautiluses

·         Still retain exterior shells.

·         Have about 90 arms that lack suckers but are rather sticky.