MARINE THINGS THAT BITE AND STING ZOOANTHIDS AND HYDROIDS

One of the most fascinating things to do during a visit to the coast is go exploring rock pools. We are very fortunate on the coast of KZN that our marine life is profuse and as a result rock pools provide fascinating glimpses into a much larger world. Our advice is to take a diving mask and snorkel, and something to kneel on. In this way one can simply don the mask and stick one’s face into the water. It looks a bit undignified so if you would rather lie full length, go right ahead. If the pools are large, the more adventurous can jump in and enjoy the spectacle even more. Above all be aware that most living organisms in these pools are delicate and easily damaged.

We remember leading a group on such an exploration trip at Mission Rocks near St Lucia. An enthusiastic elderly lady was seen on her hands and knees with her head ducked deep into a pool, with all manner of strange but joyful noises coming up the snorkel pipe. When we asked her how she was doing she emerged and sat back on her haunches, her eyes sparkling through the dripping glass of her mask. “I never realised what a wonderful world lay so close at hand!” she exclaimed. “Thank you so much for giving an old lady such a great gift. All those years gone by and I never gave it a thought.”

A wonder-world indeed lies in almost every rock pool on our coast. There are amazing life-forms under your very feet. But like all good things, there are a few creatures to be wary of. The problem is that in the marine environment so many living creatures look like marine plant-growth. Some do indeed sting, but others can upset the unwary rock-explorer simply by being slippery. Protect your feet when walking on rocks, as apart from barnacles and mussels, the rocks themselves can be very sharp.

A sheet of zooanthids coating a rock but with barnacles protruding

Chief amongst the slippery group are the zooanthids. These encrust many rocky areas in the intertidal zone, forming vividly coloured sheets of living organisms that compete for space with mussels and barnacles. If it was simply a matter of slipping on the zooanthids it wouldn’t be a problem seeing as they are quite soft. The problem lies with the sharp shells of the barnacles and mussels growing amongst the zooanthids, and these can give some quite nasty cuts if one lands on them. Cuts from barnacles and other sharp-shelled marine organisms need to be thoroughly disinfected and kept clean otherwise there is a real risk of an infection setting in.

One of many species of stinging hydroids

Some of the hydroids, on the other hand, look exactly like tiny, brownish ferns. They are distantly related to the bluebottle and are also a colony of polyps some of which are feeders, some have a reproductive function and others have stinging cells similar to the bluebottle. These are often seen amongst the innocuous seaweeds such as the segmented green Halimeda cuneata and reddish coralines that are such a distinctive feature of our KZN rock pools, or under the overhangs of the deeper rock pools. The treatment for hydroid stings is similar to that of bluebottles. Remember not to rinse the sting site with fresh water for if there are “unfired” stinging cells on the skin this will trigger them off and make the sting worse.

Here again, we strongly recommend obtaining a few books on seaweeds and other marine life. George and Margo Branch’s book “The Living Shores of Southern Africa” remains, in our opinion, one of the best – if not the best – books on the subject as it gives a wonderfully broad insight into the marine life of our coast. A Google search produces a great number of reference to this classic volume as well as tips on how to access a copy..

https://www.google.co.za/search?q=branch+and+branch+the+living+shores+of+southern+africa&rlz=1C1AOHY_enZA708ZA709&oq=living+shores+of+southern+africa&aqs=chrome.2.0j69i57j0.9706j0j8&sourceid=chrome&ie=UTF-8

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