Category: Crustaceans

Underwater Fact 91

Horseshoe crabs have existed in essentially the same form for the past 135 million years. Their blood is blue in colour and provides a valuable test that protect us humans from the toxins that cause septic shocks.

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Underwater Fact 76

The largest kind of crustacean, the giant spider crab of Japan, measures up to 3.7 meters (12 feet) across between its outstretched claws. The smallest crustaceans, such as water fleas, can be smaller than  0.2 millimeter (1⁄125 inch) long.

Mantis Shrimps are the only animals to have hyperspectral colour vision and are considered to have the most complex eyes in the animal kingdom. They can see ultraviolet, visible and infra-red light and different planes of polarized light. The shape of their eyes allows them to see things with three different parts of the eye at once.

Harlequin Mantis Shrimp   © p@ragon

They are aggressive predators and feed mainly on small fish, other crustaceans and molluscs that they are able to strike with acceleration of up to 23 metres per second. The shock wave from the force can be enough to stun or even kill the prey. Some larger species with hammer-like claws have even been known to break the glass of aquariums.

Underwater Fact 56

Crabs’ eyes are on stalks like periscopes that perceive polarised light and have a view of the whole 360 degree panorama around them.

It supports providing compass information for navigation and enables them to judge distance while the stalks fold away into protective grooves when the crab enters the burrow.

Underwater Fact 43

15 % of crabs are left-handed, the same percentage as humans.

 Ghost Crab   © Sophia Volzke

The Ghost Crab (Ocypode Cordimanna) is common to the sandy beaches of the Australian East Coast. The nocturnal crab has a translucent creamy coloured body which is where it’s name comes from. The bigger claw of this young male indicates the one preferred.

Underwater fact 36

Movember has come to an end and now it’s time to remember the most famous Mo-Stars of the underwater world:

Moustache Fish   © Sophia Volzke

#1 The Catfish’s barbels help it search for food in murky water.

#2 Antennae are the organs of touch and feel of a Crayfish.

#3 Male Mexican Mollys grow aesthetic moustaches to attract females.

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