MARINE THINGS THAT BITE AND STING: OYSTERS, BARNACLES AND MUSSELS

OK – none of these organisms bite or sting. In fact they are all pretty tasty if properly prepared, and are quite nutritious. So what’s the big deal here and why have we listed them? The answer to that is simple. Each of these organisms has a razor sharp shell that can inflict some nasty cuts on the unwary or clumsy person walking on the rocks.

There are four distinct zones along our rocky east coast shores. Each is easily identified (and named) by its most common inhabitant. The uppermost is the harsh Littorina zone where the most common organisms are three species of small, grey snails Littorina africana, Littorina krausii and Nodilittorina natalensis. A word of warning about this zone is that the rocks are often composed of limestone very roughly eroded to needle-sharp points. Please take great care when walking across these lest you trip and fall..

The next zone is known as the Upper Balanoid Zone. It is in the upper part of this zone that one finds great colonies of the sun- or Natal rock oysters. These oysters are not commonly eaten, and have a slightly raised edge to the base shell. The upper shell half fits snugly inside this base at a slightly lower level. Again, these oysters pose no direct threat at all unless you trip and fall on to them, at which moment you could suffer some nasty cuts.

Natal rock oyster and barnacles clustered together. (Image from internet courtesy of alamy)

The next zone is the Lower Balanoid Zone in which occur several species of winkles and limpets. It is also home to barnacles and brown mussels. There are two species of barnacles – Tetraclita (which looks like a tiny volcano) and Octomeris which has four distinctive plates closing the opening in the base shell. Tetraclita, like the oysters, has a razor sharp edge to its base shell. Here, closer to the incoming tide, one also finds colonies of brown mussels. These do not have razor sharp shells, but they can nevertheless, inflict some bad cuts should you slip and fall onto them.

Brown mussels on the rocks – KZN coast (Photo off internet)

The bottom line here is that these organisms pose no direct threat to humans unless said humans fall or slip on the rocks. It is essential to wear appropriate footwear when walking on the rocks too. Flip-flops are very doubtful starters here simply because they offer limited protection to the feet, and can, in fact, trip the wearer up. Another point is to use footwear with soft soles. In this way it is possible to walk across most of the shell-bearing organisms without crushing them unnecessarily. Hard-soled footwear will cause a lot of damage.

Should you be unlucky enough to take a tumble on the rocks, it is essential to disinfect any cuts or abrasions thoroughly. We always used merthiolate and as a result the badge of a morning spent fossicking around the rock pools was a liberal decoration of red blotches. Again, we recommend that wonderful book ‘The Living Shores of Southern Africa’ as a guidebook to our rocky shores.

The real danger related to mussels is, of course, picking them without a licence, or when the sea is discoloured. Mussels are filter-feeders and can process an enormous amount of water in a day. Should there be any toxins or bacteria in the water this can become concentrated in the gut of the mussel. If you eat such a mussel you run a very good chance of becoming quite ill. Always enquire about local conditions before harvesting any shellfish.

The key to spending a wonderful morning exploring the rock pools is simply to take care. The rewards far outweigh the possibilities of inflicting an injury on oneself.

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