Squids are mollusks of the phylum Mollusca. Their molluscan relatives are snails, clams and other bivalves. These groups of animals seem to have little in common, for example a clam seems to bear little resemblance to an octopus. Yet all mollusks are built according to a very similar fundamental plan. They have similar internal structures including a shell-secreting mantle, a radula for feeding and many others. The embryogeny (development of the embryo) and larval development are also very similar amongst mollusks.

Squid are members of the class Cephalopoda. Other members include octopus, cuttlefish, and nautilus. The word Cephalopoda means literally, "head-foot bearing" and refers to the way the cephalopod arm appear to be attached directly to the head.

The Long-finned squid, Loligo pealei ("LOLL-IH-GO PEEL-EYE"), also known locally as the Woods Hole squid, can reach lengths of up to 24 inches. A close relative the Boreal Squid, lllex illecebrosus, also known as the short-finned squid, overlaps Loligo over some of its range. It is generally found farther north. The two squids can be distinguished by the relative lengths of the fins.

Links to Keys Common Long-finned Squid   Scientific Loligo pealei Family Loliginidae Order Teuthoidea Class Cephalopoda Phylum Mollusca

The table at left illustrates the taxonomic names for hierarchy of clades represented by Loligo. Some of these items contain links to other taxonomic information on the network. The MBL's own Keys to the Invertebrates of the Woods Hole Region, is a dynamic key based on the keys by Ralph Smith in the 1970's. The Tree of Life project in Arizona maintains a more current taxonomic tree. The blue buttons on the right side of the table link to various levels in the tree.