Mediterranean moray eel

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Mediterranean moray eel
Mediterranean moray eel (Muraena helena) from Tamariu, Spain

Mediterranean moray eel ( Muraena helena ) from Tamariu, Spain

Systematics
Subclass : Real bony fish (Teleostei)
Cohort : Elopomorpha
Order : Eel-like (Anguilliformes)
Family : Moray eels (Muraenidae)
Genre : Muraena
Type : Mediterranean moray eel
Scientific name
Muraena helena
Linnaeus , 1758

The Mediterranean moray eel ( Muraena helena ) is a hidden, nocturnal predator of the moray eel family (Muraenidae). The Swedish naturalist Carl von Linné first described Muraena helena in 1758.

features

Schematic drawing of Muraena helena (A. Beuttner, modified from Bauchot (1987) does not claim to be complete).

The body of the Mediterranean moray eel is elongated, laterally flattened, and anteriorly compressed, giving the moray eel a snake-like appearance. Its head is short, massive and appears convex in the dorsal profile. Muraena helena has two pairs of nostrils, which lie one behind the other and are tubular. The anterior and posterior nostrils are connected by channels in which sensory cells are embedded that allow the animals to perceive odorous substances in extremely low concentrations. This gives M. helena an extremely good sense of smell . The upper and lower jaws of the Mediterranean moray eel are of the same length. They are occupied by long, pointed and conical (conical) teeth. The gill openings are narrowed and limited to small, lateral openings. The anus is slightly in front of the center of the body. The Mediterranean moray has between 139 and 143 vertebrae. The dorsal fin (dorsalis), the anal fin (analis) and the caudal fin (caudalis) are connected to a circumferential fin border, with the dorsalis beginning a little in front of the gill openings. The pectoral fins (pectoralia) and the pelvic fins (ventralia) are completely absent. Muraena helena has scaly, leathery and slimy-smooth skin . The lateral line organ , with which the animals can perceive movements, is concentrated on the head.

The coloration of the Mediterranean moray eel is very variable and can differ considerably between the individual individuals. The basic color is chocolate brown, more or less dark, with regular black, yellow, cream or white spots. The gill openings and the corners of the mouth are black-rimmed.

The largest captured Mediterranean moray eel was 150 cm tall, but Muraena helena usually only reaches a length of about 80-130 cm. The heaviest animal ever caught weighed 6.5 kilograms and the oldest animal ever caught was 38 years old. The animals normally live to be around 12–15 years. In order to determine the age of the animals, the ear stones ( otoliths ) can be dissected out.

distribution and habitat

Distribution of Muraena helena highlighted in orange (Figure: A. Beuttner, modified from IUCN, 2017). The Mediterranean moray can be found mainly in the coastal region.

Muraena helena is widespread in the entire Mediterranean , as well as in the east Atlantic from the British Isles to the Strait of Gibraltar . Their distribution area continues along the coast from Morocco to the Gulf of Guinea and also includes the Canary Islands , the Azores , the Cape Verde Islands and Madeira .

The habitat of the Mediterranean moray eel consists mainly of rocky coasts with many crevices, caves, holes and places protected by overhangs or algae, which they use as hiding places. It occurs in shallow water from a depth of a few meters to a depth of 100–300 m. According to Matic-Skoko et al. (2011) Muraena helena is said to penetrate even deeper waters of less than 600 m in order to spawn there in summer.

behavior

A Mediterranean moray eel shows its open mouth. This behavior is often wrongly interpreted as a threatening gesture by the moray eel. In reality, the moray eel opens its mouth to allow adequate breathing. On the right side of the body you can see a gill opening, which is reduced to a small lateral pore (Photo: T. Machts 2017).

The Mediterranean moray is hardly active during the day and hides in crevices or caves. Her active time begins at dusk when she goes hunting. She can then also be found free-swimming outside of her hiding place. Muraena helena is relatively true to location, but it usually has several shelters in its territory where it can withdraw.

If the moray eel is in its hiding place, usually only its wide open mouth looks out. This is often misinterpreted as an aggressive defensive stance of the moray eel. In reality, the mouth has to be opened wide enough to ensure sufficient breathing, since breathing is difficult due to the narrowed gill openings. In general, the Mediterranean moray eel shows a very calm behavior. It can only show aggressive behavior when it is strongly harassed, hungry or even harpooned by humans.

nutrition

Octopus vulgaris (Class: Cephalopoda) from Tamariu, Spain. Cephalopods are possible prey of the Muraena helena .

Muraena helena is one of the top predators in the rocky, benthic communities . It feeds carnivorously , with its main prey consisting of benthic fish (Osteichytes), but also cephalopods and crustaceans, which it prey on either as a stalker ("sit and wait") or through active search ("foraging"). Muraena helena also manages to devour large prey with ease. The Mediterranean moray eel usually hunts at night and retreats to their hiding places during the day. However, she has also been seen hunting during the day. When hunting, it hardly relies on its sense of sight , which is not particularly well developed, but mainly perceives its prey through its well-developed sense of smell .

Moray eels use a certain tactic to get prey from crevices. They form a knot with their body that they use as an abutment. With this they support themselves in order to pull their head and prey through it. They are also able to tear pieces out of large prey if they are too big to be swallowed completely.

Reproduction and development

Muraena helena is a gendered (gonochoristic) species. The reproduction of the Mediterranean moray eel takes place in the warm season (summer time). The females lay eggs 5 - 5.5 mm in size, from which a Leptocephalus larva hatches (described by Grassi, 1913). The Leptocephalus larva is a laterally flattened, transparent larval stage, which is found not only in moray eels, but also in eels, bones ( Albula vulpes ), tarpon (genus Megalops ) and female fish (Elopidae). The leptocephalus larva of the moray eel is unique in its morphology, because the larval stage of moray eels shows reduced pectoral fins (pectoralia), whereas in other eels the pectoralia are only reduced in the adult stage. The pelagic larval stage of M. helena can last up to 2 years. The Leptocephalus larva remains in the plankton . The larva can also grow to considerable size with minimal metabolic metabolism , which is an unusual but successful development strategy.

At three to ten years old and around 80 cm in size, the Mediterranean moray eel becomes sexually mature, mates and then migrates away from the coast to a depth of less than 600 m to spawn. The sexual maturity of animals can be recognized by the gonads . If there are no gonads yet, the animals are not yet sexually mature. You can recognize mature females by their large orange eggs. Mature males, on the other hand, can be recognized by their large, white testicles.

Enemies

Muraena helena is considered one of the top predators and is very high in the food chain. As a result, it has hardly any natural enemies. Nevertheless, you can find larger predatory fish such as B. large shark species become dangerous. In addition, humans represent a threat that should not be underestimated, as M. helena is sometimes used as food fish or ends up as bycatch.

meaning

In ancient Rome, Muraena helena was an extremely popular food fish. Nowadays, however, it is of little importance as a food fish. It is sometimes offered boiled, fried or baked. The skin of the Mediterranean moray eel can be made into leather. In addition, M. helena is often kept and displayed in public aquariums.

Due to the limited use of the Mediterranean moray in fishing and exhibition purposes, it is not exposed to any major threat (Red List). According to the IUCN (2017), Muraena helena is classified as "Least Concern", so no species-specific conservation measures are taken. Nevertheless, there are some marine protected areas in which M. helena occurs and thus benefits from the protected area.

Man and moray eel

Contrary to popular belief, the bite of a Mediterranean moray eel is not poisonous. Muraena helena has no fangs or poison glands in the oral cavity. Nevertheless, the bite of a moray eel is not entirely harmless, as contamination of the bite wound by z. B. skin mucus or saliva of the moray eel can lead to secondary infections. Bacteria of the genera Pseudomonas and Vibrio are particularly present in the saliva of moray eels . So to treat a bite wound sufficient, in addition to a local wound care a dose of appropriate antibiotics which are resistant Pseudomonas - and Vibrio - directed ways, be quite beneficial. Moray eel flesh can contain poisons such as organochlorine pesticides. These organic pollutants can spread globally due to their lipophilic properties and their resistance to decomposition. They are suspected of causing endocrine and reproductive disorders and cancer. Once the organochlorine pesticides have been released into the oceans' ecosystem, organisms with a higher trophic level, such as B. Muraena helena , accumulate high concentrations of the poison. The blood of the moray eels, like the blood of all eels, contains poisonous proteins . If the meat is to be eaten, it must be heated to at least 75 °.

In ancient Rome, moray eels were kept in large numbers in aquariums as a popular food fish. Many anecdotes are associated with their attitude, in which the extravagance of the owners of these animals is often discussed. Most likely, Muraena helena was the most common species of moray eel. It is considered to be the most adaptable type of rocky coast and the descriptions of an eel-shaped shape, without fins and gills, best fit the Mediterranean moray, with its completely reduced pectoral and ventral fins and the remaining fins that have grown together to form the fin edge, as well as the narrowed gill slits.

Individual evidence

  1. ↑ a b c d e f g h Whitehead, PJP, Bauchot, M.-L., Hureau, J.-C., Nielsen, J. & Tortonese, E .: Unesco three-volume publication "Fishes of the North- eastern Atlantic and the Mediterranean "(FNAM). (No longer available online.) Formerly in the original ; accessed on October 1, 2017 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.@1@ 2Template: Dead Link / speciesidentification.org  
  2. ↑ a b c d e f g h i j Bergbauer, M. & Humberg, B .: What lives in the Mediterranean? Identification book for divers and snorkelers . Franckh-Kosmos Verlags-GmbH & Co., Stuttgart 1999, p. 230 .
  3. ↑ a b c d Lichtenberger, L .: Morays in the sea water aquarium. In: Koralle, marine aquaristic book series . Natur und Tier Verlag, 2008.
  4. ↑ Göthel, H .: Fauna marina del Mediterráneo. Ediciones Omega, Barcelona 1992, p. 319 .
  5. ↑ a b c d Schmidtlein, R .: Observations on the way of life of some sea animals within the aquariums of the zoological station . Biodiversity Heritage Library., Naples Zoological Station 1878.
  6. ↑ a b c d Jiménez, S., Schönhuth, S., Lorano, IJ, González, JA, Sevilla, RG, Diez, A. & Bautista, JM: Morphological, ecological, and molecular analyzes separate Muraena augusti from Mureana helena as a valid species. Copeia, 2007, p. 101-113 .
  7. ↑ a b c Matic-Skoko, S., Tutman, P., Petric, M., Skaramuca, D., Dikic, D., Lisicic, D. & Skaramuca, B .: Mediterranean moray eel Muraena helena (Pisces: Muraenidae ): biological indices for life history. Aquatic Biology, Vol. 13, 2011, pp. 275-284 .
  8. ↑ a b Muraena helena in the endangered Red List species the IUCN 2015 Posted by: Smith, DG, 2011. Accessed January 28, 2018th
  9. ↑ Quéro, JC, Porché, P., Vayne, JJ: Guide des poissons de l'Atlantique européen. Les guides du naturaliste. Delachaux and Niestlé, Lonay, Switzerland 2003.
  10. ↑ Lloris, D., Rucabado, J .: Guide FAO d'identification des espèces pour les besoins de la pêche. . Guide d'identification des ressources marines vivantes pour le Maroc. FAO., Rome 1998.
  11. ↑ BLACHE, J., CADENAT, J., STAUCH, A .: Clés de détermination des poissons de mer signalés dans l'Atlantique oriental (entre le 20e parallele N. et le 15e parallele S.). Faune tropicale. Office de la recherche scientifique et technique outre mer (ORSTOM), 1970.
  12. ↑ a b Randall, JE & Golani, D .: Review of the moray eels (Anguilliformes, Muraenidae) of the Red Sea. Bulletin od Marine Science 56, 1995, pp. 849-880 .
  13. ^ Smith, DG & Böhlke, EB: Muraenidae. Pp. 136-148. In: Quéro, JC, Hureau, JC, Post, A., Saldanha, AE (eds.) Check-list of the fishes of the eastern tropical Atlantic and the (CLOFETA). Vol. 2. JNCIT, Lisbon, SEI, Paris, and UNESCO, Paris. 1990.
  14. ↑ a b Hixon, MA: Predation as a process structuring coral reef fish communities. In: Sale PF (ed) The ecology of fishes on coral reefs. Academic Press, San Diego, CA: 475-508., 1991.
  15. ↑ Matic-skoko, S., Tutman, P., Marcejla, E., Skaramuca, D., Đikic, D., Lisicic, D., Skaramuca, B .: Feeding habits and trophic status of Mediterranean moray eel, Muraena helena L., 1758 in the Adriatic Sea-Preliminary Approach. Rapport de la Commission internationale pour la mer Méditerranée 39: 583 p., 2010.
  16. ↑ Sallami, B., Ben salem, M., Reynaud, C. & Capapé, C .: Diet of mediterranean moray, Muraena helena (Actinopterygii: Anguiliformes: Muraenidae), from the northeastern tunisian coast (central mediterranean). Actoa Ichthyologica Piscarotia 44 (4): 273-283. 2014.
  17. ↑ Azzurro, E., Pais, A., Consoli, P., Andaloro, F .: Evaluating day-night changes in shallow Mediterranean rocky reef fish assemblages by visual census. Marine Biology. 151 (6), 2245-2253. 2007.
  18. ↑ Fish Elson, L .: Comparative gonad morphology and sexuality of the Muraenidae (Pisces, Teleostei). Copeia 1992 (1): 197-209. 1992.
  19. ^ Smith, DG: Guide tot he Leptocephali (Elopiformes, Anguilliformes and Natocanthiformes). NOAA Technical Report NMFS Circular, 424. Department of Commerce, United States of America: 19-22. 1979.
  20. ↑ Reece, JS, Bowen, BW, Smith, DG, Larson, A .: Molecular phylogenetics of moray eels (Muraenidae) demonstrates multiple origins of a shell-crushing jaw (Gymnomuraena, Echidna) and multiple colonizations of the Atlantic Ocean. Molecular Phylogenetics and Evolution 57: 829-835. 2010.
  21. Jump up ↑ Ribbins, WD, Hisano, M., Connolly, SR, Howard Choat, J .: Ongoing collaps of Coral-Reef Shark populations. Current Biology 16 (23), 2006, pp. 2314-2319 .
  22. ↑ a b Frimodt, C .: Multilingual illustrated guide to the world's commercial warm water fish. Fishing News Books, Osney Mead, Oxford, England., 1995.
  23. ↑ Triay-Portella, R., García-Martín, V., Martins, A. & Almeida, N .: By-catch composition of the striped soldier shrimp Plesionika edwardsii (Crustacea: Decapoda: Pandalidae) experimental fishery in the Cape Verde Islands . Food and Agriculture Organization of the United Nation, 2014.
  24. ↑ a b Schmölcke, U. & Nikulina, EA: Fish farming in ancient Rome and their change in reputation in the light of the political situation. In: Writings of the Natural Science Association for Schleswig-Holstein, 70 . 2008, p. 36-55 .
  25. ↑ Erickson, T., Vanden Hoek, TL, Kuritza, A. & Leiken, JB: The emergency management of moray eel bites. Annals of Emergency Medicine 21 (2): 212-216., 1992.
  26. ↑ Duffy, JE, Carlson, E., LI, Y., Prophete, C. & Zelikoff, JT: Impact of polychlorinated biphenyls (PCBs) on the immune function of fish: age as a variable in determining adverse outcome. Marine Environmental Research 54: 559-563. 2002.
  27. ^ Smith, AG & GangolliI, SD: Organochlorine chemicals in seafood: occurrence and health concerns. Food and Chemical Toxicology 40: 767-779 . 2002.
  28. ↑ Dikic, D., Mojsovic Cuic, A., Jurak, G., Lasic, D., Skaramuca, D., Matic-Skoko, S., Tutman, P., Bosnir, J., Franjevic, D., Franic , Z., Fuchs, R. & Skaramuca, B .: Organochlorine pesticides in Muraena helena L. 1758 from the Eastern Adriatic Sea. Journal of Applied Ichthyology: 1-6. 2013.

Web links

Commons : Muraena helena  - Collection of images, videos and audio files