Aalen

Group 11: Alan

Aalen

Groep 11 - Aalen: Hoewel ze op slangen lijken, zijn Aalen vissen. Er zijn verschillende soorten paling, en we zullen er twee bekijken: tuinpaling die in holen in het zand leeft en murenen. Murenen hebben een slechte reputatie, voornamelijk vanwege het voortdurend openen en sluiten van hun scherpgetande mond. Dit is echter geen bedreiging voor duikers, omdat deze actie water door hun kieuwen pompt. De meeste palingen zijn eigenlijk heel schuw.

Cortez Garden Eel (anguila jardin, Heteroconger digueti)

The garden eel spends its time waving its upper body from its sandy bottom hole. When seen from a distance, colonies of this eel can look much like a garden of grass. Upon approach the thin bodied garden eel will slowly retreat into its hole until it completely disappears. (Size 8-12”, max 20”)

Jeweled Moray (morena pinta, Muraena lentiginosa)

The jeweled moray is a commonly seen smaller eel. Small golden spots have a dark outline and can be thought of as jewels on the body. (Size 12-18”, max. 24”)

Zebra Moray (morena cebra, Gymnomuraena zebra)

The zebra moray is a shy reclusive eel that feeds primarily on crabs and other crustaceans. The teeth are much more rounded for the crushing of these shells. Its obvious black and white ringed markings give it the name zebra moray. (Size 14-24”, max 30”)

Panamic Green Moray (morena verde, Gymnothorax castaneus)

The green moray is the most common of the morays and can get quite large. Very gregarious and curious, the green moray will often swim completely out of its rocky habitat to visit approaching divers. The opening and closing of the moray’s mouth is a act required for respiration and should not be thought of as a threat. (Size 2.5-3.5 feet, max. 4.5 ft)

Tiger Snake Eel (Myrichtys tigrinus)

Distinct pattern of large round dark spots on a pale cream body. In habits sand and mud areas adjacent to reefs, searching for prey in crevices and under rocks or buried beneath sediment with only eyes and nostrils showing when inactive. Max size 75 cm.

Starry Moray Eel (Echidna nebulosa)

The Starry Moray has a thick body that tapers gradually toward the tail. They are white with 2 rows of large black blotches and black spots between the blotches that become more linear with maturity. Their head is unmarked before the eyes, affording a “beak-like” appearance. Their eyes and nostrils are yellow. Their head is broad with a short snout, short jaws, and tubular nostrils. The Starry Moray is a benthic species found within rocks, corals, and crevices of intertidal reefs at depths up to 47 m (155 feet). They will also enter shallow lagoons. They reach a maximum of 80 cm (2 feet 6 inches) in length.

Yellowedge Moray Eel (Gymnothorax flavimarginatus)

Moray eels are long slender fish with bulbous heads, rounded snouts and gradually tapering tails. The large mouth contains a single row of small pointed teeth in the lower jaw and several vomerine teeth on the roof of the mouth. The dorsal fin extends continuously from just behind the head along the back to round the tail, where it continues as the caudal and anal fins. The yellow-edged moray can grow to a maximum length of about 240 cm (90 in), but a more typical length would be 80 cm (30 in). The yellow-edged moray occurs in the tropical Indo-Pacific region. The yellow-edged moray is usually a solitary fish, tending to hide in a crevice or submerged in the sediment with just its head protruding.

Finespottet or Speckled moray eel (Gymnothorax dovii)

A moray eel found in the eastern Pacific Ocean and along the Central American coast from Costa Rica to Colombia. It is also found in the Gulf of California. It reaches a length of about 170 cm.

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1. Disks and Ovals / Colorful

The first category of disk and oval shaped fish are very important to learn. They are colorful, large and very obvious and the three main families that make up the group can be found on almost every dive.

2. Silvery Fish

Silvery fish have many different family members, though we will look at just a few representatives. As opposed to the colorful butterfly, angel and surgeonfish, the silvery fish tend to blend in better in open water and are usually not found near the colorful bottom.

3. Sloping Head / Tapered Body

This third group of “fish-like” fish, are very important to learn. The are common on most dives and are also highly sought after as food fish. It is especially important to monitor these fish to provide data for fisheries management. Snappers can be very difficult to tell apart from the similarly shaped grunts. One helpful hint is to look at their tails. Snappers tend to have straight, flat tails. They are also known for their habit of snapping their mouth open and shut when caught on hook and line. They have very sharp canine teeth that can provide a nasty bite to the unsuspecting angler. Look closely on your next dive and you may see the small teeth protruding from the side of the mouth. Grunts on the other hand, have slightly notched tails. They get their name from the grunting sounds they emit when threatened. These sounds are created by rubbing together bony teeth plates located in the back of the throat. Since the teeth are in the throat, a diver will never see protruding teeth on a grunt, only big blubbery fish lips.

4. Small Ovals / Damselfish

While divers tend to first notice the larger, more obvious fish on a dive, after a short while the challenge to find new species leads them to change their search image to look for smaller, previously unnoticed fish. Generally, the first new species a diver will encounter will belong to the small oval shaped group. This group is broken into the damselfish and their close cousins the chromis. Damsels are like the surgeonfish in that they eat algae. They do not roam around grazing, but rather tend to small algae gardens like a farmer. These areas are guarded fiercely as the algae farm is the damsels food source. For that reason you can think of the damselfish as not just territorial, but Dam- selfish with its territory. Many damselfish have distinctly different colors as juveniles, often being much brighter and more colorful when they are young and becoming drab with age. (much like us humans!) For this reason, the juveniles have been heavily collected for the aquarium trade and are under heavy fishing pressure. As part of the REEF Fish Survey Project, divers are asked to monitor the juveniles and adults separately in two of the damselfish species – the Cortez damselfish and the giant damselfish.

5. Heavy Body / Large Lips

Heavy bodied, large lipped fish belong to the seabass family. We tend to refer to the larger seabasses as groupers and the smaller seabasses as bass or basslets. These fish are extremely important food fish and are under increasing threats from heavy fishing pressures. Monitoring these fish can help provide valuable data to aid in their protection. Most seabasses are hermaphrodites, meaning the same fish will be both a male and a female during its lifetime. The groupers are all born female and later change sex to become male. Most large groupers also congregate each year to spawn at a specific location, making them easy targets for emerging positioning and fishing technology.

6. Swim with Pectorals / Obvious Scales

The fish in this group all use their pectoral fins to swim with rather than the traditional tail swimming of most other fish. The scales are also quite large and obvious. These fish can also be hermaphrodites, like the groupers, with some fish changing sex and others staying the same. Intermediate and adult fish often have very different appearances compared to the always-male terminal phase. This means learning two colors to be able to ID the same species of fish. Most of the pictures shown in this curriculum are terminal phase males, unless noted.

7. Redish / Big Eyes

This group of reddish fish is normally not seen during day dives due to their nocturnal nature. The reddish color helps them blend in at night and the large eyes help them to see better.

8. Small, Elongated Bottom Dwellers

The small bottom dwelling fish often make up the most interesting fish to watch during your dive. Their approachable nature and interesting behaviors make them great fishwatching finds. Blennies tend to be slightly larger than gobies, but are most easily recognized by their curved body posture and expressive faces. Gobies, though similar in their habitat requirements, tend to sit flat and straight on the bottom. The jawfishes actually live in a burrow in the sand that they excavate and maintain.

9. Odd-Shaped Bottom-Dwellers

This category of fish is made up of families and species that didn’t quite fit anywhere else due to their unique body shapes.

10. Odd-Shaped Swimmers

This group of fish contain families that are unusual in their shape, but are swimmers rather than bottom dwellers.

11. Eels

Though looking like snakes, eels are fish. There are several different types of eels, and we will look at two – garden eels that live in burrows in the sand and moray eels. Moray eels have a bad reputation mainly due to the constant opening and closing of their sharp toothed mouths. However, this is not a threat to divers, as this action pumps water through their gills. Most eels are actually very shy.

12. Sharks & Rays

Even though the sharks and rays are cartilaginous (their skeletons are made of cartilage instead of bones), they are still referred to as fish and count during our surveys.

5 Fun Facts - Eels

Murenen, wetenschappelijk bekend als Muraenidae, vormen een wereldwijd verspreide palingfamilie. Deze familie omvat ongeveer 200 soorten, verdeeld over 15 geslachten. Hoewel ze overwegend marien zijn, vertonen sommige soorten een voorkeur voor brak water, en een select aantal leeft in zoetwateromgevingen.

Murenen vertonen opportunistisch en vleesetend gedrag en jagen voornamelijk op kleinere vissen, krabben en octopussen. Er zijn met name waarnemingen geweest van een gevlekte murene die een koraalduivel opeet zonder enige schade op te lopen. Hun beperkte aantal roofdieren omvat tandbaarzen, barracuda's en zeeslangen, waardoor veel murenen, vooral de grotere soorten, tot toproofdieren binnen hun respectieve ecosystemen zijn gekomen.

Toothy Grin: Murenen staan bekend om hun angstaanjagende uiterlijk, met scherpe tanden en een voortdurende uitdrukking met open mond. In tegenstelling tot wat vaak wordt gedacht, ontbloten ze niet hun tanden in agressie, maar ademen ze voortdurend, terwijl murenen hun mond gebruiken om water over hun kieuwen te pompen.

Meester van de Nacht: Veel murenen zijn nachtdieren en geven er de voorkeur aan om te jagen en hun omgeving te verkennen onder dekking van de duisternis. Hun scherpe reukvermogen en uitzonderlijke vermogen om elektrische velden te detecteren, helpen hen prooien te lokaliseren, waardoor ze bekwame nachtelijke roofdieren zijn.

Kleurrijke karakters: Murenen vertonen een verbluffende reeks kleuren en patronen, van de gevlekte patronen van de mozaïekmuren tot het levendige geel van de geelgerande murene. Deze unieke markeringen dienen zowel als camouflage als voor soortidentificatie.

Langlevende legendes: Sommige murenen hebben een indrukwekkende levensduur, waarbij bepaalde soorten wel 30 jaar of langer kunnen leven. Door deze lange levensduur kunnen ze een belangrijke rol spelen bij het handhaven van het evenwicht van hun respectieve ecosystemen.

Nieuwsgierige mythologie: In verschillende culturen hebben murenen hun weg gevonden naar folklore en mythologie. Sommige verhalen schilderen ze af als beschermers van de zee, terwijl anderen ze associëren met mystieke krachten. Hun mysterieuze uiterlijk en gedrag blijven verhalen en legendes over de hele wereld inspireren.

Aalen

Group 11: Alan

Aalen

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5 Fun Facts - Eels

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+ 506 8610 0914

Playas del Coco, Hoofdstraat 151
Guanacaste, Costa Rica

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