A short story about elasmobranchs

At that time as student of marine biology I was getting knowledge about many things of seas. Most of them used to be like war news (and now I suppose they’re even worst) and we all in my classroom were facing how to figure out ongoing and future environmental challenges, with questionable outcomes and poor results. After all we were only students, but with feelings to fight environmental challenges beside scientists! Global warming, ocean acidification and overfishing are only the most famous posters. Week after week questions were arising in my mind and with unknown sense of guilt I was wondering how to give a personal contribution. How to be part of a concrete change. How to “fight” on the field, feel “boots on the ground”. It occurred to me a group of researcher from my university I had been working with as intern. Among their projects there was the ideal one. The project was called Scuba Tourism for Environment. It was my occasion.

Few months later I was standing in front of a dozen of tourists teaching them the biology of coral reefs and what all the awesome creatures were doing during that light lesson before the snorkelling. I was in Marsa Alam. In Egypt. In the Red Sea. Hosted by TGI diving I did my best to spread knowledge of that ecosystem to all and everything was paying me off. Few months after the end of the former experience I was doing the same job. Again. This time in Sharm El Sheikh. Again in Egypt and yes, again in the Red Sea.

I still remember vividly. I was alone, early in the morning to have a quick look around the reef in order to spot good sights for the later snorkelling. With mask and fins on I jumped down and a few seconds later, after bubbles were thinned out, I saw two eagle rays right there, only 10 meters beneath my nose. Yes! eagle rays! Well, they are not eagles that live at the sea but it is a common name that refers to animals similar to skates, but instead of laying on the sea bottom they often swim in the water column moving the two sides of the body like wings. Their head remembers that of eagle indeed the name comes from here! Perhaps they even don't like it but of course, the head’s shape is exactly like that!!

After a couple of minutes of pure excitation, I started to breathe and swim. Such a feeling. I got more peace in that moment than in any moment during my life. Just me and them. I remember so much that event because those two peaceful eagle rays were the first elasmobranch I observed in my life. Yes, we must exclude those ones I sighted into aquariums! Elasmobranchs. An elder, mysterious, intriguing, wild and unique group of… fish? Are they fish? I mean, they don’t seem to be fish! But above all, what elasmobranch (I know I know, it is even difficult to say!) means? Elasmobranch is simply the name of a group of animals similar to common fish. Sharks, the most famous actors, belong to this enigmatic Elasmobranch group. Now I’ve caught your attention, did I? Beside sharks though there are also other animals like rays, less famed (have a look at the bottom of the picture below). I don’t want to bother you upon dozens of things on these animals, my intention is to spot differences with what from now on we will call fish (what we should usually eat let’s say twice a week as the Mediterranean diet teach us) and why they are good to know.

1. Elasmobranchs don’t have "true" bones! Certainly, they must rely on something “hard” you might think (they don’t look like worms!). You are surely right, indeed they have a skeleton but instead of being calcium-based like ours (“drink your milk! It is good to grow up” mum used to say many years ago!) it is made out of cartilage. Thus, no fish bones stuck in throats. Anyway, better not to eat to them! Why?

2. Elasmobranchs have not much sexual appeal to each other. Hey I’m just kidding you!! However, there is a kernel of truth. Most of them adopt another strategy with respect to fish in fact sexual maturity is usually reached late during the life. Moreover, instead of broadcast millions of eggs and sperms into ocean currents where fertilization occurs (like most of fish) females jealously brood a few puppies who once born they are like small adults, already prepared to catch preys! Such predators, aren’t they? We now could understand the reasons why is better not to eat elasmobranchs: they give much less births than fish by comparison and the eventual probability to eat an individual who did not contributed yet to the next generation (by basically… having sex with females of its species) is high!

3. Recognizing males from female is usually easy! Once reached the sexual maturity the males experience a transformation in pelvic fin’s morphology indeed they becomes more elongated and harder. I can’t hide that they look like two sausages! Thus, next time, no matter if in an aquarium or during a wild excursion, when you will see sharks or skates just pay attention at the pelvic fins (those at the bottom of the belly towards the tail)!

I have always supported scientific divulgation through short stories because it makes learning process lighter and fluent as the information flow in mixed with anecdotes. However, I could not tell you all this story without the people who made that possible. A very very big thank you to the Marine Science Group of the University of Bologna for involving me two times in STE project and to TGI diving with all its staff for hosting me lovely, I felt at home during the time together.