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Penis fencing flatworms

Deep inside the oceans watery floor, there live many animals which are mysterious and dramatic. We might have only learnt a small amount of the kinds of life forms in the oceans and are already bewildered. Today we are going to learn about small creatures that are flat, soft-bodied and freeliving in the waters. While most of them are parasitic and seek nurturing from other organisms, their spongy structure is interesting as in most marine flatworms, there is no body cavity present!

The little worms are found near the coral reefs and are tiny on size (less than an inch). Their vibrantly colourful, flattened oval body shape with a pair of short tentacles on the head makes them a sight to behold as they swim away hurriedly. Marine flatworm’s flamboyant colours are perceived to aid in showing off their toxicity to other predators like the fish.

Reproduction in marine flatworms

Marine flatworms are hermaphrodites which means they have both male and female reproductive structures. This comes as a challenge as when they are looking to mate. There is a very good advantage to being the male and not the female as the male practically doesn’t have to worry about guarding, rearing and safeguarding the offspring after the mating procedure is done. This is quite different for the female as they have a lot more responsibility.

The mating happens with a fight. Each of the flatworms has two penises. When a pair of worms meet, they try to fence their penises at each other to inject sperms and avoid getting inseminated themselves. This type of duel can go on for hours, and the transfer of the sperms happens with the stab wounds. The worm that can infuse his sperm into their partner first is the winner and is the father. The winner, of the penis fencing, will not just father more offspring but will also have fewer wounds to heal.

The penis stabbing trick

The worm that is stabbed and carries the sperm becomes the mother and starts behaving accordingly – caring, feeding, protecting. In a paper published by Michiels and Newman 1998, it was observed that the fathers are rewarded with direct access to the eggs while the mother must bear deep wounds and loses any control over the sperm’s access to the eggs.

In the animal kingdom, making love looks more like war, but tenderness is found in unexpected places. Many animals have some of the weirdest and unusual ways of reproducing. But that’s what nature is all about.


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