Its host is a ball by day and a net by night, and the shrimp lives on both.
A basket star spends daylight folded into a tight knot wedged in the reef, and after dark unrolls into a filigree of thousands of branching arms held across the current, catching plankton. That is a huge structure appearing and disappearing on a twelve-hour cycle, and a one-centimeter shrimp living in it goes from being inside a fist to being on an open lattice a meter across.
Which means the animal has to do two completely different jobs. Folded, it is buried inside the tangle and utterly safe. Unfolded, it is out in the current on a moving surface, in the dark, with the host doing the feeding - and it takes its share directly from the arms.
That is why nobody sees it. Basket stars are only open at night, they are only in current, and the shrimp is a centimeter of brown banding on a brown banded arm.
Find a basket star on a night dive and look along the thicker arms near the center.
- one centimeter, brown with pale banding matching the host's arms
- clings to the branched arms of a basket star
- invisible while the host is folded up
- up to 1 cm
