A zoea larva of the brackish water crab Rhithropanopeus harrisii from Noordzeekanaal, Netherlands. With three long spines on his nose and one on its back it protects itself against predation by fish.
Description
Crustaceans such as crabs, lobsters, shrimps and hermit crabs often also have larvae that spend the first weeks of their life in the plankton. In the first stage, the zoea stage, the larva looks completely different from the adults, often with long protrusions so as not to be eaten and to sink less quickly. After moulting a few times, the larva changes into the megalopa stage, where it already looks like a mini crab or lobster. The megalopa looks for a place on the bottom to live on.
Crab larvae, especially the megalopas, are real predators, they eat all kinds of other animals in the plankton. The megalopa can already grab large prey with its claws. Crab larvae are often massively present in plankton samples at the end of spring.
Several zoea larvae of crabs, with on the left a larva of (probably) a shrimp.
A larva of a hermit crab, caught in the North Sea.
A megalopa larva of a crab from the North Sea.
A larva of a Norwegian lobster Nephrops norvegicus, caught in the North Sea. Nice spoiler!