The good, the bad and the prickly

The good, the bad and the prickly

Beautifully strange in form, members of the Echinodermata phylum appear to drift between plant and animal. However, these unusual organisms are actually more closely related to humans than plants, or even insects. This animal group includes some of the most “sea-like” animals such as seastars, but also less appreciated ones like sand dollars and, my personal favourite, sea urchins. Echinoderms vary greatly in what they do, some being voracious predators and others preferring to graze on seaweed. But despite their differences, most echinoderms have a thick, hard skin, often coated in spines, thus giving them their scientific name: echinoderm, or ‘hedgehog skin’.

Image: CSIRO Publishing

During my own studies, I worked on an echinoderm species and began to appreciate this animal group as a whole. As I watched my sea urchins peacefully chomping on their algae pellets, I often thought of time-lapse videos of seastars chasing down their prey. I thought of how striking some sea cucumbers are and how others looked, well, like something that came out of your rear end. I quickly realised that echinoderms encompass some of the most amazing and diverse species on Earth. If you disagree, I’m sure a look through Australian Echinoderms: Biology, Ecology and Evolution would sway your opinion.

Part photo guide, part reference, Australian Echinoderms is a useful text for scientists and sea enthusiasts, or just anyone who wants to learn about Australia’s echinoderm species. The book’s editors, Maria Byrne and Timothy D. O’Hara, help describe over 130 families of echinoderms within Australia, including their habitat, biology and distribution.

This expertly compiled book is full of information – nothing seems to have been forgotten. Covering not only the very many species found in Australian waters, the text also makes comparisons between different groups and gives information on where they are found and how they affect the ecosystem around them.

A common sight on many Australian beaches, these skeletons, or ‘tests’ as they are more formally known, belong to sea urchins, a kind of echinoderm. Image: Trish Koh

When I received the book, I eagerly flicked to the passage about the species on which I was then working: the Purple Sea Urchin, Heliocidaris erythrogramma. I found this section incredibly easy to read, and full of useful and accurate information backed up by references that would help further my understanding of the species.

But what stands out the most in this book are the images. Painstakingly gathered and resulting in a veritable list of illustrators and photographers, these photos and scientific illustrations are what make this reference accessible to anyone, not just researchers. My personal favourite is an underwater image of a seastar, resting upon a rock and surrounded by seaweed – the very archetype of the sea. The use of images is no doubt the best way to show the diversity and beauty of echinoderms.

I am probably one of the few who has dedicated two years to studying a particular echinoderm, and I am often questioned about why I would choose to spend so much time looking at a spikey rock. But to me, echinoderms are really quite special, and this book does a far better job of explaining the incredible nature of these unusual animals than I ever will.

Another type of echinoderm, sea cucumbers or holothurians are perhaps most well-known for their ability to eviscerate. This is a defensive strategy that involves the sea cucumber ejecting its internal organs when threatened. Image: Cathy Cavallo

Australian Echinoderms will soon have a home on my coffee table, not because the book is particularly light reading or superficial, but because it’s the greatest way to share my love for echinoderms. Now, anyone who comes into my home can have a flick through this comprehensive book and begin to discover the wonderful world of these unique animals – the ones covered in ‘hedgehog skin’ – for themselves.

You can purchase your copy of Australian Echinoderms from CSIRO Publishing.


Banner image courtesy of Cathy Cavallo.

Trish Koh

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