Science Snippets

Ocean Friends

In the Indian Ocean, there are many strange things. One of them is the relationship between the Randall’s Pistol Shrimp and their friends the gobies.

Randall’s Pistol Shrimp. Photo uploaded to Wikimedia Commons by Hkchan123. CC BY-SA 3.0

The shrimp are only a couple of inches long, and they are striped red and white like candy canes. They have large claws, which they use to capture food and to dig burrows for themselves in the sand and gravel at the bottom of the sea. They push the sand around like little bulldozers and carry larger pieces of gravel in their claws. By hiding inside their burrows, the shrimp can avoid the big fish and other predators that might want to eat them.

To dig the burrows, however, they have to push sand and gravel out onto the seafloor. When they come out, they might get eaten by predators. And they can’t see the predators coming; they have very poor eyesight. In fact, they can hardly see at all.

To solve this problem, the shrimp get help from a small fish known as a goby. There are many different kinds of gobies; they are small, brightly colored fish. They would also like to hide from predators, but they can’t dig burrows like the shrimp can. The gobies do have very good eyes, so they can see predators coming from a long way off.

By working together, both the shrimp and gobies can stay safe. They live together in the burrow that the shrimp build. The gobies act like watchmen. All day long, the gobies stay just outside the burrow keeping an eye out for predators. If a goby sees a predator coming, it will quickly dart into the burrow.

Gobi (Amblyeleotris yanoi) and shrimp (Alpheus randalli). Photo by Steve Childs, from Flickr via Wikimedia Commons. CC BY 2.0

When a shrimp comes out pushing a load of sand or wants to walk outside the burrow to find some food, it drapes one of its long antennas over one of the gobies. Even though the shrimp can’t see, their antennae are very sensitive. If the shrimp feels the goby dashing back into the burrow, it will know that danger is near and will also head into the burrow.

If the shrimp gets lost outside, a goby will even guide it back to the burrow. Some gobies will also bring pieces of algae home for the shrimp to eat.

Have you ever seen any animals working together to get something done?