The California giant sea cucumber (Parastichopus californicus) is commonly found along the Pacific Coast of North America. It grows up to 50 cm in length and the tube feet along its dorsal side are reduced to papillae and warts.
It has recently been discovered that this species of sea cucumber feeds using its anus. Thanks to this new knowledge, it has been proposed that numerous species of sea cucumber feed using their butts. Scientists have coined the term “bipolar feeding” to describe this behavior.

(Source)(Source)

The giant triton (Charonia tritonis) is one of the very few animals that eats the crown-of-thorns starfish, itself a voracious predator and destroyer of coral reefs. This gastropod is an active hunter that will chase prey, such as starfish, mollusks, and sea stars, once it has been detected. It uses its muscular single foot to hold its victim down while it cuts through any protective covering using its serrated, tonguelike radula; it then releases paralyzing saliva into the body before eating the subdued prey.

(Photo by Dimitrios Poursanidis)

The largest and heaviest of all mollusks is the giant clam (Tridacna gigas). Like other bivalves, it feeds by filtering small food particles from the water using its ingoing, or inhalant, siphon, which is fringed with small tentacles. However, it differs in obtaining most of its nourishment from zooxanthellae (the same dinoflagellate algae that form a symbiotic relationship with many species of coral). The algae have a constant and safe environment in which to live; in return, they provide the clam with essential nutrients, the carbon-based products of photosynthesis. In fact, so dependent is the giant clam on these algae that it will die without them.

Photo © Christoph Specjalski

The whale shark (Rhincodon typus) is a graceful, slow-moving giant and the largest fish in the world. At 1.5 m wide, its mouth is large enough to fit a human inside, but it is a harmless filter feeder that eats only plankton and small fish. Accounts of these giants describe sightings of individuals up to 20 m in length.
To obtain the huge amount of food it needs, it sucks water into its mouth and pumps it out over its gills, where particles of food become trapped by bony projections called gill rakers and are later swallowed. This shark has the thickest skin of any animal, at up to 10 cm thick. Prominent ridges run the length of its body, and it has a large, sickle-shaped tail. The pattern of white spots on its back is unique to each fish, enabling scientists, through analysis of photographs, to identify individuals. While little is known of their ocean trabels, satellite tagging has shown that some whale sharks migrate across entire oceans. Whale shark eggs hatch inside the mother, and she gives birth to live young that reach up to 60 cm in length.
Every year, around April, whale sharks migrate to Ningaloo Reef off northwestern Australia for a plankton feast. The plankton explosion results from a simultaneous mass spawning of the reef’s corals, possibly triggered by the full moon.
Whale sharks are killed for their meat and fins (used in soup), although they are legally protected in some countries. 

Photo © Ken Knezick & Erik Schlögl

Unlike most sea spiders, which have a leg-span of less than 2.5 cm, the giant sea spider (Colossendeis australis) has a huge leg-span of about 25 cm. It has a large proboscis through which it sucks its food, but its tiny body is so small that the sex organs and parts of its digestive system are situated in the tops of the legs. Sea spiders are somewhat unusual among arthropods in that they exhibit parental care, the males having a modified pair of legs to carry the eggs until they hatch.

Photo © Claudia Arango

Known as the saltwater crocodile, estuarine or Indo-Pacific crocodile (Crocodylus porosus), this formidable predator is the world’s largest reptile, and is also one of the few crocodilians that frequently swims out to sea. Its power and ferocity are legendary, and it is thought to be responsible for more than 1,000 human deaths per year. The saltwater crocodile has powerful jaws housing teeth up to 13 cm long. Its immensely tough skin is covered with thick scales. The scales on its back are armored with bony deposits called osteoderms, while its tail has a double row of upright bony plates (scutes). Its nostrils close when it dives, but it cannot exclude water from its mouth. Instead, it has a valve at the entrance to its throat, which opens only when it swallows food.

It controls its body temperature by cooling down in water and warming up in the sun. Like other large crocodiles, the saltwater crocodile hunts by stealth, lurking close tot he shore, hiding beneath the water with little more than its eyes and nose visible. When an animal comes within range, it bursts out of the water with explosive force, grabs its victim, and then drags it under until it drowsn. Crocodiles cannot chew their food—instead, they tear it to pieces, digesting scales, skin, and even bones. Their natural prey includes birds, fish, turtles, and a wide variety of mammals, such as wild boar, monkeys, horses, and water buffalo. Females lay up to 90 eggs in a waterside mound, carrying their young to the water when they hatch. Saltwater crocodiles are hunted in many parts of their range, making large specimens rarer than they once were.

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*Note: I didn’t write this description and I think it’s a lot of fear-mongering. Blame it on the AMNH. 

The Giant’s Causeway is a tightly packed cluster of some 40,000 columns of basalt (a black volcanic rock). It’s located at the foot of a sea cliff that rises ninety meters on the northern coast of Northern Ireland. Although legend says the formation was created by a giant named Finn McCool, it in fact resulted from the volcanic eruption some sixty million years ago, one of a series that brought about the opening of the North Atlantic. The eruption spewed up vast amounts of liquid basalt lava, which cooled to form the columns. They are up to thirteen meters tall and are mainly hexagonal, although some have four, five, seven, or eight sides.

(Source: tourismontheedge.com)

The fin whale is the second largest creature on Earth, reaching maximum lengths of 82 feet (25 meters) for males and 89 feet (27 meters) for females. Fins are baleen whales: They use the fringelike baleen in their mouths to strain krill and tiny fish from the massive amounts of water they ingest as they feed.

Photograph by Daisy Gilardini

Often mistaken for a jellyfish, the Portuguese man-of-war is actually made up of a colony of organisms working together. Its tentacles can extend 165 feet (50 meters) below the surface, although 30 feet (10 meters) is more the average.

Photograph by Jennifer Kiewit

A giant spider crab is illuminated by the lights of a submersible. Protected from some predators by its hard exoskeleton, the creature—which can grow to ten feet (three meters) wide—can also blend in with the ocean floor. Under deeper cover, it can disappear beneath the sponges and other marine life it uses to adorn its shell.

Photograph by Emory Kristof