Meroplankton are organisms that spend only part of their life in the plankton in the larval or early stages. Many bottom dwelling animals have meroplanktic larvae in a wide range of taxa ranging from worms to sea stars and sea urchins, snails and bivalves to the crustaceans. The larvae have often bizarre, strange shapes quite different from the adult form. Some larvae only stay in the plankton for hours, while others spend many months floating around before they settle down.
Why have meroplanktonic larvae?
An advantage of having meroplanktonic larvae is that the larvae can disperse over wide distances with currents, so the organisms can colonize a large area. Also if the meroplanktonic larva feed in the plankton the adults have to invest less energy per egg and can produce more eggs.
Disadvantages of having a meroplanktonic stage are that many larvae are lost because they are eaten, starve, or end up in places unsuitable for settlement. To counter this, organisms with meroplanktonic larvae release many larvae, often in the thousands to millions per individual.
In below gallery you can see an overview of the wide range of meroplankton taxa, shapes and forms.