It can be hard to see what type of creature the giant ostracod (Gigantocypris) is at first glance. It looks like a large, organge ball, and is found all around the world – in deep, dark and cold oceans.

The Giant Ostracod, swimming in the ocean mesopelagic zone.

Their bodies can consist of up to 95% water, which is comparable to jellyfish. However, they are not jellyfish at all, but rather crustaceans! Although they might not look like it, ostracods are a type of shrimp. They also go by the name “seed shrimp”! Characteristic of seed shrimps, is that they are surrounded by a translucent, bulbous shell. This shell is reminiscent of a mussel shell, or a seed, and has a small opening of which the ostracod can extend small antennae, used for both movement and catching small prey.

Ostracods are usually quite small, around 1mm in size – however giant ostracods are the largest of its kind, becoming up to 32mm. This might sound small to us humans, but for the other zooplankton floating in the mesopelagic zone, it is just like a giant. They have two giant golden eyes, which they can use to look right through their shell. They likely use these large eyes to detect and hunt bioluminescent prey in the deep sea – including fish larvae, copepods, and arrow worms.

In this close-up picture, you can see the seed shrimps large bubble-like shell, and two golden eyes. In addition, antennae are portruding from the shell opening, allowing the giant ostracod to swim and catch prey.

Female giant ostracods also utilize their shell to protect their eggs and developing embryos. Thus, they give birth to developed offspring that resemble miniature adult shell shrimps! With their abnormally large eyes, and bulbous shell covering their entire bodies, the giant ostracod is well adapted for life in the ocean mesopelagic zone worldwide.

Are you interested in learning more about the incredible life in the ocean mesopelagic zone? Check out our latest animated video below, and keep an eye out for more Creature Spotlights!