Скачать или смотреть The Midnight Zone - Sawtooth and Snipe Eels

Hi members! This is a sneak peak extract from a film I'm working on about the Midnight Zone (bathypelagic) of the ocean, spanning waters from 1,000 to 4,000 metres down (3280 - 13123 ft) where the light of the sun is completely absent.

Efficiency is key in the ocean, and every aspect of an organism’s anatomy and behaviour is optimised to solve the challenges they face. Body shapes of fish are incredibly important!

In the sunlit waters of the high seas, predatory fish spend most of their lives on the hunt. Water is 800 times more dense and 50 times more viscous than air, making it a challenge to move through. It helps to be streamlined, with a rigid forked tail, like that of tuna. This is a fusiform body type. It minimises inertial drag and allows tuna to migrate more than 15,000 kilometres in a year, at times reaching 43 miles per hour.

Fishes of coral reefs are compressed. They require agility, not speed, and so are flattened side to side for quick, accurate turns and darting among coral and rock.

On the sandy sea floor, fish are flattened (think flatfish), with depressiform bodies and a downward-facing mouth.

So what about down, down, down in the ocean’s midnight void? Being a streamlined predator would be unsustainable, owing to the low food availability. There is no rock to dart among for cover, ruling out the advantages of compressiform fish, nor any floor to feed, so no depressiform fish. Instead, there are two body types that seem to dominate. Rounded globiform fish, like the anglers, suited for floating in wait of prey to come within reach.

And anguilliform bodies - elongate and flexible - like that of the sawtooth eel (Serrivomer spp.) and snipe eel (Nemychthis spp.), shown in this clip.

This form not only allows these fish to conceal their silhouettes by hanging vertically, but enables them to move in a series of sinuous waves that pass along the body and produce propulsive thrust for efficient swimming.

In the slender snipe eel, the jaws of its birdlike beak curve away from each other at their tips, covered with tiny hooked backwards-pointing teeth for trapping minute crustaceans like shrimp as the beak sweeps through the water, permanently agape.

The snipe eel also boasts the most vertebrae of any animal on earth - with more than 700 running along its metre-and-a-half long body.

As fishes like these move, flexible throughout their entire length, the undulatory wave passes backward with increasing amplitude and speed, producing the highest propulsive thrust in the tail. It offers the most efficient method of locomotion in a place so starved of energy, without compromising on speed as the anglers have.