The Blobfish

Blobfishes occupy a habitat some 2,800 metres (9,200 ft) beneath the waves – a zone that's exposed to incredible pressures. Because they're such deep divers, these animals have a number of physical adaptations for dealing with the harsh conditions. For starters, blobfish bones are extremely soft, and therefore less prone to cracking.

Many fish use an air-filled swim bladder for buoyancy, but that's a dangerous piece of kit for a deep-sea fish, as changes in pressure could expand the swim bladder, forcing the other internal organs out of the mouth. Instead, blob sculpin rely on their gelatinous flesh – which is slightly less dense than seawater – to stay afloat.

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The fish have very little built-in structural support, so it's all that deep-sea pressure that actually holds everything together.

When hauled to the surface, however, blobfish encounter a rapid pressure drop, and the anatomy that works so well at great depths suddenly turns on them, expanding and falling into a gooey mess.

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On a dive off the coast of northern California, the team encountered a blob sculpin (Psychrolutes phrictus) and watched on as the fish guarded a brood of tiny, pink eggs.