LSM1303 Animal Behaviour Student Blog

Now, what could this be?

a) An inflatable float.

b) A breathing apparatus.

c) A Jellyfish.

 
Answer: d) None of the above.

What this inflatable jellyfish like animal is an invertebrate, the Man- of –war. It does have a rather impressive name, but IS IT impressive?

As I have found out from this article, it is indeed extraordinary.

The Man- of – war is not exactly ONE animal, but is actually a floating hydrozoan, which consists of four types of polyps. The four different simple animals that form the Man- of – war are the float, the tentacles, the feeding zooids and the gonozooids which produce gametes for reproduction.

Click here for more information on polyps.

These different polyps work together to form an intelligence system that functions as a whole. Each polyp has a different function, which helps in the survival of the Man- of – war. For example, the float polyp helps in the locomotion of the Man- of – war. It is like a sac filled with nitrogen, and acts as a “sail” to drift the animal in the direction of the wind and tide. This is also where the Man- of – war derived its name from, as it resembles an olden day battle ship.



With all these different animals living “under the same roof”, one must wonder why they do so and how they do not feel a competition for resources.

Each polyp has different needs and functions. Other than the “sail”, one other part is for reproduction, while the remaining two parts function as the hunting and digesting tool.

Man- of – wars are hermaphrodites; each individual gonozooid consists of male and female parts. The fertilised egg develops into a planktonic larva which then reproduce in large quantity by asexual budding.

The most powerful part of this combined animal is the tentacles, not only do they contain a painful sting which can be fatal, they are also used to catch and trap small sea creatures which will then be slowly dissolved by enzymes secreted from the underside of the float.

As you can see, these four simple animals coexist as “one organism” because the benefit of doing so greatly outweighs the cost involved. Although a single animal has a function by itself, it will never be able to survive alone, as it lacks other necessary functions for survival.

I find this animal really amazing because it has managed to survive even without doing much. There’s no need to swim as the “sail” helps in drifting. Eating for this animal is also like a simple task as it simply traps and dissolves its prey; absolutely no need for foraging or stalking. In addition, there is no need for MATE- SELECTION, a process which many other animals spend alot of time and energy engaging in.

At this point, we wonder what could possibly lead any fish to swim through the deadly tentacles of the Man-of –war.

The answer?



The Nomeus gronovii.

This fish shares a symbiotic life with the Man-of-war.

Want to see the Man- of- war in action?

Man-Of-War Podcast!

Remember to look out for the Man-of –war fish, as well as the enemies of the Man-of-war.

Here's some trivia:

As compared to a jellyfish, the man-of-war is a giant.

As compared to a grown man...

it STILL is a giant!!