ISOPOD LIFE CYCLE:

Adult females carry eggs and developing young in a pouch under the body. Once the young hatch, they undergo a few moults before leaving this protective enclave.

They depart the pouch as an active swimmer, but have only a relatively short period before needing to attach to a host of their own and return to a sedentary lifestyle.

This explains the phenomenon by which some reefs seem completely infested by these parasites. Every individual in a school can be infected as larvae leave the pouches of mature females and infect the fishes around them.

Copepods

Copepods are the other most commonly seen marine external parasite. Like most parasites, they have closely related freeliving relatives that are a very common element of zooplankton. They feed on the host’s mucous and tissues as well as directly on their blood. Large females are usually noticed, as they frequently have a pair of eggs coils coming off their body. The male is usually too small to see with the naked eye.

Parasites are easily overlooked, but I suggest on your next diving trip you keep an eye out for these fascinating creatures. There are more species of marine parasites in the Coral Triangle region than anywhere else on Earth. As much as they might make you squirm, they too contribute to the extraordinary diversity that makes coral reefs one of the most biodiverse ecosystems on the planet.

TOP A scorpionfish stricken with a large copepod parasite, sporting a pink swirl of eggs, attached to its eye. The parasite itself is even adorned with a tiny barnacle of its own MIDDLE Shrimps also suffer from parasites. This isopod has deformed the...

Richard Smith, is a British marine biologist and underwater photographer who aims to inspire appreciation for the ocean's fascinating inhabitants. More of his work can be found at www.oceanrealimages.com.