Granular sea star at Fisherman's Beach

Sea life: Starfish

One of my favourite things to see when I’m lying on the sand during a dive (waiting for Tony’s students to finish skills, for example) is a starfish making its way from one point to another. They don’t look like speedy movers, but they are – in this effortless gliding way that belies the fact that hundreds of little tube feet are working hard to get them where they want to go.

Sand sea star
Sand sea star at Long Beach

Like anemones, starfish have hydrostatic (comprised of water) skeletons. Their mouth is underneath, where their legs meet up, and they expel waste from the top of their bodies. They have what’s called a sieve plate, next to the anus, that they use to draw water into their bodies.

Reticulated sea star at Fisherman's Beach
Reticulated sea star at Fisherman's Beach

I didn’t know this until I started diving, but starfish don’t just stay as small as the little cushion stars you see in rockpools. We’ve seen ones as large as dinner plates, often in huge congregations like a social meeting. Windmill Beach is a particularly good place to see piles (literally) of starfish.

Pile of starfish at Long Beach
Pile of starfish at Long Beach - picture by Tony
Cushion star at Long Beach
Cushion star at Long Beach

Starfish are pretty voracious eaters. For example, they like mussels, and will use constant steady pressure with their legs to force the mussel shell open a bit. Then they extrude their stomach (handy skill) into the mussel shell, and digest it in situ. Whenever you see a starfish hunched up over something, it’s eating. We have seen one trying to digest a tennis ball at Long Beach… Poor guy!

Munching star fish
Munching star fish at Long Beach... hope it's not eating a golf ball!
Starfish and whelk
Starfish and whelk locked in mortal combat at Long Beach

The rumours are true about starfish being able to survive if they lose legs. We’ve seen one with two legs lying in a gorgeous if slightly gruesome heart shape (our wedding starfish!), and one with six (I think sometimes the “regrow leg” gene goes a bit haywire and doesn’t know when to stop).

Our wedding starfish at Long Beach
Our wedding starfish at Long Beach

There are a few starfish varieties to see in Cape Town, and worth a look, even though they might seem boring and common…

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Clare

Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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