What kind of mollusk includes squid and octopuses

Squids use their two long tentacles to catch prey and eat it in chunks. How they look: Octopuses have a mantle, rounded head, rectangular pupils on their two eyes, eight arms, and come in a wide variety of colors while squids have two fins at the top of their mantle, a triangular head, circular pupils on their eyes, a rigid backbone-like structure called a pen, and a combination of arms and tentacles, which have hooks and suckers.

Their appendages: Octopuses have eight arms covered in suckers while squids have eight arms and two longer tentacles used to catch fish and shrimp in open-ocean waters. Octopus arms are more flexible than those of a squid, allowing them to walk, handle objects, and manipulate their environment. Defenses: Some species of squids can expel clouds of ink into the water for a quick escape when they feel threatened while an octopus can change colors to hide or squeeze their bodies into the tiniest of crevices or objects like shells.

Reproduction: Male octopuses use a specialized arm the hectocotylus to transfer sperm to a female, who then lays groups of eggs in strings that might resemble decorative strings of holiday lights in her den. Females will guard the eggs until they hatch, which can be anywhere from 30 days to one year later depending on the species. Chitons crawl along rocks looking for food usually algae. A chiton uses its radula tongue to scrape algae off rocks.

It also has very hard teeth that are also used to scrape algae of rocks. These teeth are hard enough to etch glass! Embedded within their shells are primitive "eyes" that can detect light. Chitons are very, very slow moving. During a year, a chiton may move only ten feet! The Bivalves The bivalves class Bivalvia are very well known.

They include clams, mussels, oysters and scallops. All bivalves have two shells the name means "two shells" , and there are about 15, species.

Most bivalves do not have radula because they eat by filtering water through their gills to obtain organic particles. Most bivalves attach themselves to something or burrow underground. Some scallops, however, do not attach themselves to anything and are able to swim by squirting water through their mantle.

How Are Pearls Made? Phylum Mollusca Class Cephalopoda Cephalopods are a group of molluscs that include the pearly chambered Nautilus, squids, and the octopus. They can be divided into three categories: the Nautiloidea chambered Nautilus , the Ammonoidea the extinct ammonites , and the Dibranchiata squids, the extinct belemnites, and octopuses.

Ammonite fossils occur in places in the Cretaceous of Delaware. An ammonite can be thought of as an octopus stuffed inside a straight, coiled, or spiral shell. Most of the larger coiled ones are found in the Merchantville Formation. Sections of the straight-shelled Baculites are more common in the Mount Laurel Formation. The belemnite species Belemnitella americana is the Delaware State Fossil. They are amber colored, bullet-shaped fossils that served as the internal skeleton in an extinct squid-like animal called a belemnoid.