On the bottom
In a recent swim, my swim buddy discussed the different starfish. It was delightful to learn that the 11 arm starfish were local ones, not the purplish invasive species. Immediately after this discussion, farther out in 6 meters water depth, I spied a starfish far below on the bottom and tried counting the arms. The clarity was excellent, but I thought my mind wasn't, as on each count I couldn't make it to 11. Feeling slightly flummoxed, I stopped, then duck-dived to take a photo for a later arm count.
This star fish is actually the Eleven-Armed Seastar. While humans and most animals need complex brains to negotiate to find a mate, mating, birthing and then raising a new young baby, this amazing creature discards such frivolities. It has fissiparous reproduction where the animal divides in two to create new individuals. Well, I never. Is it no wonder that it has no heart?
It is one of the largest sea stars in Victoria. It typically has 11 arms, which would be about 25cm long, however, its arms can be different lengths or even missing due to damage. Don't worry, missing an arm? Just regenerate it. Need a brain? Not at all for starfish, nor blood. Oh, the tips and tricks of this little Victoria carnivore!
https://portphillipmarinelife.net.au/species/7769
https://arxiv.org/pdf/1202.2219
Update: Sept-2026 - Recently at Rye Pier Vadim Belakhov come across these Eleven-armed Seastars capturing an amazing tussle. Vadim wrote:
"During one of my night dives at Rye pier, I came across two enormous Eleven-armed Sea Stars (Coscinasterias muricata) approaching each other on the seafloor.
At first, I thought I was about to witness some kind of mating behaviour. But I soon remembered that this isn’t how they reproduce.
Eleven-armed Sea Stars have an unusual reproductive strategy. They can reproduce sexually by releasing eggs and sperm into the water, but they are also capable of reproducing asexually by splitting themselves in two and regenerating the missing parts.
In the meantime, the encounter turned aggressive.
The slightly larger sea star appeared to attack its smaller rival. They pushed into each other, their arms becoming increasingly entangled as they twisted, climbed over and partially smothered one another.
For animals we usually think of as slow and almost motionless, the struggle was surprisingly intense.
Then I finally saw what they were fighting over.
What appeared to be the remains of a small octopus emerged from beneath the smaller sea star.
Eleven-armed Sea Stars are predators and opportunistic scavengers. They are far too slow to chase down a healthy octopus, but an injured, dying or already dead one would be a very different opportunity.
Eventually the larger sea star won the struggle and consumed the remaining food."
The amaziing photos captured by Vadim Belakov are included below. Thank you, Vadim.
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