The Abyssopelagic Zone

 

The name of this zone comes from the Greek meaning "no bottom", and refers to the ancient belief that the open ocean was bottomless. It extends from 4000m to the sea floor. The only zone deeper than this is the hadal zone, which includes areas found in deep sea trenches and canyons. This zone is home to pretty inhospitable living conditions, which include near- freezing temperatures and crushing pressures.

 

 

 

This deep water squid is just one of the several squids and octopus that live in this zone. Note how this one is completely transparent, and has photophores on it's tentacles to attract food and warn away predators.

 

 

 

Basket stars are just one kind of echinoderm that flourish on the sea floor. Basket stars sit on the bottom, or attached to tall sessile animals, with their flexible arms raise above them to catch floating and falling organic particles. Their arms are quite fragile, but can regenerate quickly. This specimen has an armspan of over 25cm.

 

 

The seapig is a rather grotesque looking relative of the sea cucumber, another echinoderm. These are one of the most common macroscopic animals pulled up in bottom dredges. They plow through and eat mud, digesting the organic particles and bacteria, much like earthworms.

 

 

 

Sea spiders are relatives of crustaceans and belong to the class Pycnogonida. They stride around the ocean bottom on their long legs and suck their meals out of sessile animals like anemones and some echinoderms with their tube-like mouth parts. Sea spiders are found at all depths along the bottom, and range in size from that of a small spider to over a 30cm leg span. (for more on sea spiders, click here)

 

 

This large shrimp is another example of a deep sea crustacean, like the bathyl amphipod. This animal has no eyes, and is coloured red, both of which are good adaptations for the lightless environment. They feed on whatever small organic bits and pieces they can.

 

Any guesses what group this weird- looking piece of flesh belongs to? Believe it or not, it's an echinoderm and is classified with sea cucumbers. The flaps on the right side of the body are wings that enable this animal to fly through the water at these great depths; a feat matched by few echinoderms. Another flying echinoderm is called the swimming cucumber, and looks just as odd its winged relative.

 

 

The last animals in our tour of the deep is this deep sea medusa, a relative of the jellyfish. It captures prey with its tentacles and digests is in its central cavity, shown here in red. There are several other groups of jelly animals that also live at this depth, feeding on small crustaceans, larva, and whatever organic debris trickling down from above that hasn't been nabbed in its drop of kilometers.

 

 

 


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