I've lumped Squid and Cuttlefish together because they're so often confusted – to the point where common names are often misleading. While they have many common external features, the main difference is internal: Cuttlefish have a unique internal shell (the cuttlebone) while squid do not.
Caribbean Reef Squid
Scientific name: Sepioteuthis sepioidea
This sample was spotted in Bonaire, where I've often seem on sites around Klein Bonaire. They're usually in pairs or small groups.
Broadclub Cuttlefish
Scientific name: Sepia latimanus
This is one of the larger and more common cuttlefish you'll see around Southeast Asia. It's often camoflaged with coloring to blend with the sandy bottom, and the appearance of barbs, yet when it wants to move, the barbs disappear and the color becomes more white.
Flamboyant Cuttlefish
Scientific name: Metasepia pfefferi
Aside from it's “flamboyant” coloring, the other interesting thing about this cuttlefish is that it “walks” along the sandy bottom.
Bigfin Reef Squid
Also known as: Glitter squid, oval squid
Scientific name: Sepioteuthis lessoniana
These rather small squids can often be found at night, when they can be almost annoyingly attracted to your dive lights.
Bobtail Squid
Scientific name: order Sepiolida
The term “bobtail squid” is the common name for a large group of small squids that haven't been scientifically categorized.