(Source) 

Humboldt squid (see this previous post)

The following is an excerpt from an article, view the source to read the full version.

The monstrous squid remains motionless just ten feet away. Emotions gave way to cognitive thought and I trained my camcorder on him and begin to record. Almost on cue, he begins his approach. Then, with blinding acceleration, he lurches onto me with a powerful “thud crackle”. He slams into my chest. The impact was incredibly powerful, knocking the wind out of me. His huge arms envelope my complete upper body and camera and I can feel my chest plate move as his beak grinds against it. The crackle and scratching of thousands of chitenous ring teeth against my fiberglass/kevlar chest plate is unmistakable. 

(Photo by Brett Morrison)

Sea anemones are a group of water-dwelling, predatory animals of the order Actiniaria; they are named after the anemone, a terrestrial flower. Sea anemones are classified in the phylum Cnidaria, class Anthozoa, subclass Zoantharia. Anthozoa often have large polyps that allow for digestion of larger prey. As cnidarians, sea anemones are closely related to corals, jellyfish, tube-dwelling anemones, and Hydra. A sea anemone is a polyp attached at the bottom to the surface beneath it by an adhesive foot, called a basal disc, with a column shaped body ending in an oral disc. Most are from 1.8 to 3 centimetres (0.71 to 1.2 in) in diameter, but anemones as small as 4 millimetres (0.16 in) or as large as nearly 2 metres (6.6 ft) are known. They can have anywhere from a few tens to a few hundred tentacles. A few species are pelagic, and are not attached to the bottom; instead they have a gas chamber within the pedal disc, allowing them to float upside down in the water.

(Source)

(Source of photo here) Lightning whelks (see this previous post)

Giant clams (see this post)

fuckyeahbranchs:Flabellina affinis_02 by Guillem Mas on Flickr. For unicornpizzadough.

Flabellina affinis (nudibranch) see this previous post.

100leaguesunderthesea:Harlequin Shrimp by sbailliez on Flickr.

Harlequin shrimp (see this post)