Overview of Marine Invertebrates

Overview of Marine Invertebrates Aretha Rae Boezak Most South African fisherman depends on marine invertebrates to lure fish in order to catch them. These baits are sometimes also used commercially. Some species of invertebrates tend to be quite popular baits, whereas others wouldn’t even be considered. The use of these organisms as fishing bait can have its pro’s and con’s. The most successful baits have been exploited, especially those that are more successful as a live bait. The success of the baits may be as a result of a chemical or a scent that most fish are attracted to. Also, they are quite meaty. Marine invertebrates are some of the most fascinating organisms on the earth. They are found in a variety of locations and is of extreme ecological importance to most marine organisms. It has been found that a vast number of organisms feed on these invertebrates, as they are quite nutrient rich. Marine invertebrates are classified into 12 different phyla. These include: Porifera, Cnidaria, Ctenophora, Platyhelminthes, Nemertea, Nematoda, Rotifera, Annelida, Molluscs, Arthropoda and Echinodermata. Some popular invertebrates that are not marine are spikes (also called maggots), meal worms and wax worms. Spikes are th e larvae of some fly species, whereas meal worms are the larvae of the darkling beetle species and wax worms, that of moth or bee moths. The phyla Nematoda, Annelida and Molluscs are the most popular invertebrate baits. The rest are not as popular as fishing baits. The reason for this might be as a result of defensive attributes or assets that those organisms have. Some of these include Cnidarians. Cnidarians mainly use chemicals as a defensive attribute. Some contain dreadful neurotoxins that can be fatal to both man and animal. Though some fish species that feed on these organisms are consumed by mankind, it might seem a bit too dangerous to use them as bait. Some are just as dangerous dead or alive. The problem isn’t the bait itself or fish that might be spoiled, it is the handling of the organism. Given that some fisherman are uneducated or do not pursue in the danger of handling these organisms. In South Africa invertebrates like mussels, lug worms and mud prawns are amongst the famous baits for both anglers and commercial fisherman. Commercially, mostly vertebrates are used as bait depending on the type of fish that are caught. Pelagic fishes like hake and common fish in the Cape, like Kabeljou/kobs, can be lured with invertebrates as bait. Annelids like lug worms are also commonly used for bait. Lug worms belong to the class Polychaeta and are found in rocky shores. Lugworms live in sand mixtures where it forms a U-shaped burrow. They are also called burrowers and are tremendous when fishing for Kabeljou, Spotted gunter, White- and Red stumpnose, Dageraad, Yellowbelly Rockcod, Slinger, White steenbras, Hottentot and Bronze. Another is the free swimming Polychaet, Alitta succinea, commonly known as Rag worms (also known as the pile worm or clam worm). Rag worms are a marine annelid that belongs to the family Nereididae. They can be found on the bottom of shallow marine waters. These worms are an important nutrient source for crustaceans and bottom-feeding fish. Arenicola loveni, commonly known is the blood worm. These belong to the family Arenicolidae. Though they are endemic to South Africa, blood worms is an example of an over exploited bait. They are found in estuaries, where they dig deep, u-shaped burrows with one end forming a funnelled depression. According to Branch et al.(2010: 70) â€Å"water is drawn through the tube, oxygenating the sediment and encouraging bacterial growth.† Their name was derived from the fact that they have haemoglobin present in their blood, therefore when damaged, they bleed red blood. The collection of Pseudoneires variegata, commonly known as the mussel worm is also used as bait, but it’s collection destroys large areas of mussel bed. The Wonder-worm (Eunice aphroditois) and the estuarine wonder- worm (Marphysa elitueni) are also amongst those used as bait. However, the bite of the wonder-worm can inflict pain as it is carnivorous and has large jaws. Both these worms gravel under boulders, but the estuarine wonder-worm also burrows in sandbanks. There are a number of molluscs that fish find palatable. Molluscs work particularly well when fishing for snoek, natal stumpnose and the most common fish in the Cape shore, Galjoen. The only problem with molluscs is the possibility of destroying beds, which destroys the habitat of other organisms as well. Mussels are the most common belonging to the class Bivalves. Branch et al. (2010:146): â€Å"As the name implies, bivalves are enclosed by a pair of shell valves, hinged together along the back by an elastic ligament and extending down on either side of their body.† Mussels are a good bait to use when angling in rocky shores. Fulvia papyracea, commonly known as pencil bait, also known as Razor shells, make tremendous bait. They burrow themselves deeply in clean, firm sand of lagoons and estuaries. Cephalopods like squid are also used as bait. There are also a few famous crustaceans in the bait community. These include crabs, shrimp and prawns. Most anglers also use mud prawns, Upogebia Africana, as bait. These are one of South Africa’s few macro benthic invertebrates. Being very much exploited, mud prawns are found all the way form Lamberts Bay in the West coast to Maputo in Mozambique. These are limited to distribution as a result of temperature tolerances. These species are only found in estuaries that are connected to the ocean or at least exposed to the ocean for the majority of the time. Ecologically, the mud prawn is quite of importance in the estuarine ecosystem. This is as a result of their burrowing and filter feeding. The exploitation of these organisms can lead to severe eutrophication of the estuarine, because of the diverse effects on micro algae and bacteria . There are laws concerning the gathering of the invertebrate organisms gathered as bait in South Arica. With regards to angling, these baits are protected by limitations on number, size and method and by licenses in KwaZulu-Natal. The number per day for bait organisms are: Black mussel 25 ;Bloodworm 5; clam 8; limpet 15; mud crab(giant) 2; other crabs 15; octopus 2; oyster 25; periwinkle 50; polychaete worms 10; prawn(mud and sand) 50; pencil bait 20. Instruments with a blade width of 38mm or less may be used to remove limpets or black mussels and polychaetes may only be dug by hand. Given the vast majority of invertebrates are marine; they can be used for fresh water fishing as well. Fresh water invertebrates can also be used for marine fishing. In South Africa marine invertebrates have proven to be the best fishing bait for anglers, as some species can be used for all types of fishing. However, by using them as bait they are sometimes exploited and can have severe effects on a whole ecosystem. References Beer, A. Maar, D. 2007. Marine fish sea creatures. London: Hermes House. Branch, G M. 1978. The living shores of Southern Africa. Cape Town: C. Struik publishers. Branch, G.M., Griffiths, C.L., Branch, M.L. Beckley, L.E. 2010. Two Oceans. Cape Town: Struik Publishers. Edwards, A. Prichard, M . 1978 . Fishing for beginners. London: William Collins sons and company ltd. 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