As humans we think of men and women as entities with fixed genders. Fish do things a little differently from what we might think of as normal.

Most of us have eaten grouper for dinner or in a sandwich at some point in our lives, but did you know that most grouper change their gender as they mature?

They are called protogynous hermaphrodites.

Most or all of the groupers and sea basses are born female but as they mature they change into males. In some species they adopt a herd-like breeding practice with a dominate male doing all or most of the breeding and with several sub-dominate immature males in the wings.

The domain male is the most aggressive and under fishing pressure will be quickly caught. This tends to break up the spawning aggregation if it’s late in the season. But if it happens earlier one of the sub-dominate males will quickly mature and take over as the dominate male.

If you keep on fishing these aggregations, sooner or later you’ll run out of males. The absence of enough males results in females changing into males sooner than if they weren’t fished. If the fishing keeps up they will change into males at an earlier age, resulting in fewer eggs for spawning.

The younger females produce fewer eggs than older females. The reason for the evolution of protogynous hermaphrodites is to enhance the chance for successful spawning opportunities.

The Caribbean Harlequin Bass is a simultaneous hermaphrodite. This means that they can change sex at will throughout their life. Can’t find a date? Make a change.

Some of the anglerfish have a different way of doing things. Anglerfish sit on the bottom waving a small fin that looks like a worm to attract its prey. As with most fish the female is larger than the male. In this case, much larger.

These females don’t have any problems finding a male. When the female anglerfish starts to mature the smaller male physically attaches to the female’s body.

He becomes a part of her — though he retains his own identity. When the female is ready to breed she signals the male and he complies. Talk about a kept man.

There are a very few species of fish that are monogamous and mate for life. The clown fish is one such species. The mated pair will make their nest among the stinging nettles of anemones. They are immune from the stings due to thick mucus covering their bodies. Their young are afforded protection by the anemones from predators and the adult clownfish, which are very aggressive, will drive off fish that try to prey on the anemones.

When one or the other of the mated pair dies the other never takes another mate — true love in the fish world.

Think Global – Act Local!

Dr. “Skip” Lazauski can be seen on the television show “Eco-Bites”, which airs on Mediacom’s channel 14 and Smartel’s channel 4. To reach Dr. Lazauski for questions and comments, send e-mail to IchiOrca@yahoo.com. For more information, see his Web site, drskiponline.com.