Isopod has a fishy life
MEET a real life marine monster – the tongue- biting isopod.
Ma l a y s i a n ma r i n e b i o l o g i s t Melissa Martin is spending several months investigating the Museum of Tropical Queensland’s collection of isopods, to become more familiar with the bizarre life cycle of these crustaceans, which make their permanent homes in the mouths of unsuspecting fish.
So far her review of the Townsville collection has unearthed about five new species of the parasites.
This includes one parasite that carries up to 1000 eggs in a pouch – all of them hatching into males.
Multiple isopods can infect the same fish host, but here’s where things really get strange: ‘‘ Once they attach on a fish, they will develop into adult males,’’ Ms Martin said.
‘‘ The ultimate stage is to reach female stage. If the fish host has no other female, the first male to parasitise that fish will become a female.
‘‘ What is interesting is, there will only be one female. It’s like a queen hierarchy thing.’’
There are about 10,000 species of isopods, both marine and terrestrial, inhabiting all kinds of terrains. The largest, Bathynomus giganteus, can grow as long as 37cm. It feeds as a scavenger on whale and fish carcasses at depths of about 1km.
The tongue- biting species can grow as long as 4cm, feasting on a fish’s blood through its tongue.
Eventually the parasites feed so much on the tongue, it falls off and the creature replaces the organ, by attaching its own body to remaining muscles in the host’s mouth.
The fish is able to use the isopod just like a normal tongue.
Ms Martin hoped she would be able to help the aquaculture industry find better ways of controlling the parasites in fish farms.