Invertebrates

Beneath Falklands Waters Whatever your reasons for taking up diving once you venture beneath the ocean you enter an amazing world of alien creatures and plants that have adapted to the rigours of life in the sea. This web site will give you an introduction to some of the marine life to be found beneath Falkland waters. Hopefully it will also provide some understanding of what you will come to see for yourself and to further your own personal goals in underwater exploration. If you wish to comment on any of the photographs, with additional information on the species, or because we are not perfect, we might have got it wrong (see bryozoans). Your views and contributions to our collection will be greatly appreciated.
Echinodermata This is a fairly easily recognised phylum starfish, sea urchin, feather stars and sea cucumbers. They are typified by the tube feet that are operated through a system of hydraulics. They are not colonial. SEA URCHINS Although the sea urchin is not a fast mover you find it grazing on algae and like all species it plays a vital role in the marine ecosystem to keep it in balance. The three species most commonly found in Falkland waters are the pink, and pencil urchins. The other two urchins, the naked and small urchin (diameter 30mm) are not so widely dispersed. SEA CUCUMBER Fairly widespread throughout the Falklands you can sometimes find them attached to the stalks of the Macrosystis kelp. The most common one here is yellow in colour, soft bodies and bearing a crown of tentacles. STARFISH A large number of species live in our waters and all of the starfish and brittle stars have the usual five arms. We do have some exceptions, one being the sunstar and the other being the basket star.


Crustacea The crustaceans form a huge phylum which include marine animals such as barnacles, shrimps and crabs. ISOPODS/ AMPHIPODS These are normally ignored by most divers, but if you look carefully then it can be a joy to watch them scuttle over the sea bed and for the isopod swim upside down. BARNACLES The encrusting barnacles are all normally found in areas of high energy where they are best suited to catch small food particles in the water. It is noticeable that many of the ships that do come down here to fish usually come from a warmer climate, and on inspection will be found to be fouled by either goose neck barnacles or encrusting barnacles. DECAPODS We have a good selection of decapods in our waters from the painted shrimp to the red-backed crab. Being in the South Atlantic and close to the Antarctic we do see occasionally lobster krill in large swarms. The only crab to be commercially worked is the paralomis crab.


Cnidaria The Cnidaria phylum has two common characteristics an anemone like body form and tentacles which are covered in cells equipped with stinging nematocysts. With over 10,000 known species worldwide, they vary in shape, size and the way they live their lives in the marine environment. ANEMONES These invertebrates fall into the group of cnidarians known as anthozoans which basically means 'flower animals'. In the Falklands we find many species ranging in size from a centimetre to 7/8 centimetres across. Many are found in shallow crevices whilst others are found exposed to the full turbulence of the sea. JELLY FISH Found very often in Falkland waters especially during the warmer summers. We have seen jelly fish up to half a metre in diameter. CORALS A number of species occur around the Falklands, predominantly on vertical wall faces in depths ranging from 10-30 metres. HYDROIDS These can be identified by the crown of tentacles being elevated on a stalk. What looks like a feather is in fact a number of polyps arranged along each barb. It is from these polyps that hydroids release miniature medusae at the planktonic stage in their life cycle .



Mollusca This group of Marine Invertebrates includes a hugh number of species such as snails, bivalve, sea slugs, squid and octopus. CHITONS Known as coat-of-mail shells because of the eight overlapping plates. It is a primitive mollusc which has adapted to living stuck firmly to rock like some of the other shellfish. GASTROPODS (Key Hole Limpet) Very common in our waters with the characteristic hole in the top of its shell. SNAILS Many different species of Topshell can be found in our waters, Our largest snail varies in length from 40mm to 120cm. Its footprint can be easily recognised over the flat sand, soft bottom. SEA SLUGS These are found in a variety of habitat. Like all of the smaller creatures that in habitat the ocean floor if you swim too fast you can easily miss them. There are at least six species of nudibranchs in our water. CEPHALOPODS It is quite common to come across octopus and squid whilst diving in these waters. Seals love octopus to eat and you find that they usually bring them to the surface and thrash them into pieces before eating. The two principal species of squid Loligo gahi and Illex argentinus are both fished commercially.




Porifera Believed to be plants until the late 18th Century, sponges are very simple animals and consist of colonies of millions of single celled animals. The scientific name for sponges is Porifera, meaning pore bearing. If you look at a sponge you can see the thousands of tiny pores called ostia which cover the sponge's external surface. Although sometimes very difficult to identify the more common ones found in Falkland waters are the encrusting, massive, branching and boring sponges. ENCRUSTING SPONGES Very simple body structure which forms an encrusting layer over rocky surfaces. MASSIVE SPONGES Thick, heavy and rather shapeless it is more complex in its body structure than the encrusting sponge. BRANCHING SPONGES Tendency to grow upwards and clear of the seabed. It is not found in areas of high turbulence as its tougher brothers. BORING SPONGES These sponges are found in waters normally deeper than 10m and in areas where there is turbulence. The most brightly coloured found in our waters is the Yellow Elephant boring sponge which can grow over 6 feet across. It also becomes the home of many other sea creatures as can be seen in the photograph. How old some of these large sponges are is anyone's guess.



Worms Probably the most unglamorous of marine creatures but they are very diverse and important to the marine ecosystem. Three of the most common to be found are the annelids, sediment feeders and calcareous tube worms. The sedentary worm live in burrows or tubes built from body secretions and sediment particles, this worm remains in its self-built home for life of the phylum Annelida, class Polychaetae these worms possess a feathery protrusion that extends out of the end of the tube, feeding for planktonic organisms. Other worms that have a calcerous shell take advantage of wrecks and other hard surfaces and start to coat areas of the surface with their rough white tubes.

Bryozoa Bryozoa or sea mats are composed of colonies of thousands of minute polyp like animals called zooids. Bryozoans are eaten by a variety of grazing animals such as sea urchins and various molluscs. One Bryozoa that is seen is the common sea mat which is found encrusted to kelp fronds which is grazed by nudibranchs. Beneath the kelp canopy you will find a wealth of fluffy bunches and mossy looking patches attached to the rocks and overhangs. You will have to look very close if you want to make out the tiny boxes belonging to each individual in the colony. This distinguishes bryozoans from sponges and colonial sea squirts.		Colony of bryozoa or Space creature? You tell us!
Tunicata Commonly called sea squirts they all have the same basic structure of a U-shaped bag with two funnel like openings. The tough leathery body wall of a sea squirt is also known as a tunic hence the name tunicates. Fixed to the sea bed they have to make do with whatever comes past them in the water current. Being filter feeders water is pumped in and out of the body through the two siphons one inhalant and the other exhalent. A net like filter within the body gathers food particles before the water is expelled. You will find both solitary and colonial sea squirts on all the reefs especially on vertical rock faces and from high energy sites to the more sheltered areas.

Algae Marine plants are both ubiquitous and of vital importance in the sea. CORALLINE ALGAE Single celled plants which appear as a pink encrusting layer which can cover rocks, sedentary animals. In some areas of the Falklands they have remained unattached forming rubble-like maerl beds or rounded lumps resembling pinkish rock. SEAWEEDS The green, brown and red seaweeds exhibit huge variations in size and shape. The seaweeds support entire communities of animals. By far the most conspicuous feature of the Falkland coastline is the vast area of kelp forests Macrocystis pyrifera. We tend to find this grows in water depths up to 20/25metres. Buoyed up by gas filled bladders it rises to the surface to make the most of the sunlight before it is absorbed by the sea water. Many species of seaweed attach themselves to rocky surfaces with a holdfast. Although the holdfast plays no role in the up take of water or nutrients it does provide shelter for a large number of other smaller animals.