Monday Morgue: 30th March 2009

Cuttlefish (F. Sepiidae)
Pulau Semakau, 6th December 2008

Wild Fact Sheets
Online Guide to Chek Jawa
CephBase

Instant palm trees may beautify dull Marina Barrage

A STOMPer saw these instant palm trees near the Marina Barrage may help add some greenery to the otherwise dull concrete environment there.

He said:

"This picture of some instant palm trees was taken near the Marina Barrage at Marina Mall.

"Each tree has a base covered with earth and surrounded with a large white plastic sheet, held in place by strong wire mesh.

"As this area is very windy the tree needs extra support from the white guy-ropes that run from the top of the trunk to the wooden spikes driven into the ground around the tree.

"Perhaps these palm trees are to be planted in the Gardens by the Bay (still under construction) or near the roads in the adjoining areas.

"As the Marina Barrage is mostly concrete these trees will provide a welcome change to the otherwise drab environment."

Flowers from tree keeps falling on my car

STOMPer Annoyed says that flowers from these trees planted in the carpark at Block 510 West Coast Drive, keep falling on the vehicles parked there and it is a hassle removing them.

This STOMPer says:

"This carpark is behind Block 510, West Coast Drive.

"Flowers shedding from a tree is covering the whole carpark.

"The carpark is unsightly with the flowers and it covers the entire road. It is a hassle to remove the flowers from the cars.

"I think the West Coast Town Council should not have such trees planted here.

"Hope something can be done."

Of all the stupidity recently seen on STOMP, this has got to be one of the most depressing examples. That the person who submitted this is old enough to drive, and presumably, is capable of reproducing, does not bode well for the nation.

As an aside, is it too much to ask for the editors at STOMP to at least vet the submissions and correct the really obvious spelling and grammatical errors before uploading them?

"Trail treetop walk affected by waterponding everytime it rains"

A regular jogger and visitor to the area, a STOMPer is upset that this trail leading to the treetop walk suffers from ponding, and says she hopes something can be done.

In her email to STOMP, the STOMPer said:

"I am a regular jogger at this spot, ( HSBC treetop walk, via Venus Drive ). Whenever it rains, water collected from the rain will remain at the pictured area. This location is at the start of the HSBC treetop walk, next to Venus Drive carpark.

"As you can see for yourself, visitors will have to get their footwear soiled/dirtied to cross this trail. The canopy this big tree is the cause of these, as it slows down the evaporation process of the collected rainwater. I have reported this to NEA fearing mosquitoes breeding. They replied saying they went to site to inspect, but found no breeding of mosquitoes. Still, the National Parks should do more to improve on these trails. I have some suggestions,

"1. use materials like those for constructing roads, as they will withstand the harsh weather and human traffic
2. construct a 2nd footpath outside the perimeter of this big tree, so that it would remain dry and usable at all times.

"I look forward to the relevant departments for their reply."

Great, yet another hypocrite who wants to enjoy the beauty of nature, while at the same time is squeamish about getting her shoes dirty. *facepalms*

In the first place, these puddles are able to form because of soil compaction, which results from the normal daily passage of visitors, including joggers.

If you don't wish to get your shoes dirtied while jogging, there's already a nice little network of parks, park connectors, and stadiums available.

Check out why Kusu Island is so popular with tourists

A STOMPer took a day trip to Kusu Island and was impressed with its beauty. Here are some pictures he took, which includes the famous temple known for its turtle pond. Says the STOMPer:

"This upgraded pier at Kusu Island was opened recently and every day shiploads of tourists come here to visit the turtle pond which Kusu is famous for.

"There is a pagoda and a cemented boardwalk for tourists who want to visit the temple.

"You can see three stone turtles in the temple and legend has it that in the early days when the sailors were shipwrecked, the giant turtle came to save these poor sailors.

"The live turtle pond there is kept by the temple caretaker. He feeds the turtles with kangkong everyday.

"There is also a sluice gate to the turtle pond. During the hot weather, the water dries up very fast and sea water is then let in through the sluice gate."

Kusu Island has a rich and fascinating history, and is one of our more well-visited offshore islands. Every year, during the ninth month of the lunar calendar, it is thronged with thousands of people making a pilgrimage to its temple. However, outside of this particular window of time, it is a peaceful, idyllic place, where time seems to slow down. Kusu Island then becomes an excellent location for quiet reflection and contemplation, where one can try to emulate the shelled reptiles that are so closely associated with the island.

Among its various attractions is the Tortoise Sanctuary, with its resident population of turtles released there by devotees in an attempt to gain merit. So far, I have not personally visited the Tortoise Sanctuary, but have instead explored some of the reefs fringing this island.

Based on some photographs I've seen of the island's reptilian inhabitants, most of the turtles released are red-eared sliders (Trachemys scripta elegans), a North American species that has now established itself all over Singapore and is now our most common freshwater turtle species. However, there are also smaller numbers of Malayan box turtles (Cuora amboinensis) and giant Asian pond turtles (Heosemys grandis). One wonders if the turtles are able to find sufficient food; as a whole, their slow metabolisms mean that turtles can survive on significantly less food than a similarly-sized bird or mammal, but starvation of captive turtles would be unnecessarily cruel.

Turtles have a long history that dates back to the Triassic, and while it is inaccurate to claim that they have not changed at all over the past 220 or so million years, it is apparent that they hit upon a winning formula very early on. The evolution of the chelonian shell is still a complicated mystery, with Chinlechelys and Odontochelys, 2 new fossil finds last year from the Late Triassic, presenting very contradictory views on how the shell evolved; in fact, scientists are still divided over where turtles belong in the reptile family tree in the first place.

The Testudines are a very wide-ranging group of reptiles, with members inhabiting virtually every tropical and temperate wetland environment. Many terrestrial species are well-adapted to surviving in arid savanna and scrub, or even true desert, while others have colonised offshore islands and evolved into lumbering giants.

Some confusion exists over the usage of the terms 'turtle', 'terrapin', and 'tortoise'. Locally, 'terrapin' is used for any semi-aquatic species, although I prefer to reserve the term for the diamondback terrapin (Malaclemys terrapin), an inhabitant of coastal brackish swamps on the eastern coast of North America. Here's an excellent graphic from Wikipedia that shows how the names are defined ecologically in some English-speaking countries.



Southeast Asia is particularly rich in turtle species, and Singapore itself has six native species belonging to two families, the Geoemydidae and Trionychidae.

The geoemydids are a family of terrestrial and semi-aquatic species, and range from placid vegetarians to omnivores. Four native species of geoemydid are known to occur in Singapore, the Malayan box turtle, Asian leaf turtle (Cyclemys dentata), spiny turtle (Heosemys spinosa) and Malayan flat-shelled turtle (Notochelys platynota). The local status of the painted terrapin (Batagur borneoensis), not to be confused with the unrelated painted turtle (Chrysemys picta), is indeterminate; it might or might not exist in Singapore, and we need good eyewitness accounts or at least an identifiable specimen to verify its presence. The same goes for the Malaysian giant turtle (Orlitia borneensis), although to be honest, I won't be surprised if these species, as well as several others not mentioned, do in fact exist in some of our more inaccessible waterways.

Unlike the largely peaceable semi-aquatic geoemydids, the trionychids, or softshell turtles, are almost wholly aquatic, and have a reputation for being aggressive predators. Softshell turtles lack the hard bony scutes that cover the carapace of other turtles, and instead have a layer of leathery skin. The snout is elongated to form a snorkel-like structure, enabling the turtle to breathe while the rest of its body remains submerged. Singapore has two species, the Malayan softshell turtle (Amyda cartilaginea) and forest softshell turtle (Dogania subplana), while the existence of a third species, the Asian giant softshell turtle (Pelochelys cantorii), remains unverified.

The international trade in turtles, both for food and as pets, has also resulted in several other species colonising our waters. As mentioned before, the red-eared slider is now ubiquitous in freshwater environments everywhere, from koi ponds in parks to reservoirs, and even in nature reserves.


Here is a red-eared slider that I found living in the fountain at one of the washrooms along Siloso Beach.

Recently however, it appears to have been joined by a close relative, the North Antillean slider (Trachemys decussata) of Cuba; I have seen this species in the Singapore Botanic Gardens, while Marcus has a photo of an individual that he spotted at the Sungei Buloh Wetland Reserve.


This is the North Antillean slider I saw in the Symphony Lake at the Singapore Botanic Gardens.

These two species belong to the Emydidae, which like the Geoemydidae, are a family of largely semi-aquatic omnivorous turtles, with a few terrestrial species. While the Geoemydidae are predominantly Eurasian, with a single genus found in tropical Central and South America, the Emydidae are found throughout the Americas, with a single species inhabiting Europe, North Africa, and western Asia.

The most common softshell turtle in Singapore is the Chinese softshell turtle (Pelodiscus sinensis), which is commonly bred and imported for food. This is the species most commonly used in turtle soup. Escapees from farms and releases by pet owners and religious devotees have no doubt enabled this species to establish itself in some urban and rural waterways, possibly at the expense of our native softshell turtles.


Chinese softshell turtle at Swan Lake, Singapore Botanic Gardens;
(Photo by Marcus)

Among the geoemydids, the black marsh turtle (Siebenrockiella crassicollis) is possibly a non-native species. It is now common in many parts of Singapore, and its widespread distribution is probably partly due to the fact that this species is often released by those who believe in gaining karma through releasing captive animals. Similarly, it is likely that many Malayan box turtles encountered in the wild were former captives.


Black marsh turtle at Swan Lake, Singapore Botanic Gardens;
(Photo by Marcus)


Here's a Malayan box turtle I spotted at the Symphony Lake, Singapore Botanic Gardens.


Marcus has photographic evidence of yet another non-native species, the Chinese stripe-necked turtle (Ocadia sinensis). This photo was taken at the Singapore Botanic Gardens.

The pig-nosed softshell turtle (Carettochelys insculpta) is occasionally encountered in local pet shops, although trade in this species is illegal. I was very surprised at the beginning of this year when I saw one swimming in the pond in front of the Visitor Centre at Sungei Buloh!

Most worrying though, is the presence of snapping turtles in Singapore's reservoirs. Not only is there a threat to native aquatic wildlife, but these North American species also pose a significant safety hazard. Marcus has photographed a common snapping turtle (Chelydra serpentina) in MacRitchie Reservoir, while someone was foolish enough to blog about releasing a pet alligator snapping turtle (Macroclemys temminckii) into Lower Seletar Reservoir, and was subsequently visited by the AVA. God forbid that enough of these non-native turtles are abandoned and released into our waters to establish breeding populations.


Common snapping turtle, MacRitchie Reservoir;
(Photo by Marcus)


Alligator snapping turtle being released into Lower Seletar Reservoir.
(Photo by Sukianto)

The deliberate release of animals, whether it is abandonment of unwanted pets, or a misguided attempt to gain merit for doing a supposed good deed, continues to piss me off to no end. Our native aquatic fauna is already at risk from a wide variety of threats, from loss of habitats to poaching. The last thing they need is the introduction of non-native species that will upset the ecological balance, whether it is by actively predating upon other species, competing with similar native species for food and other resources, or by spreading diseases and parasites.

Not to mention that there are ignorant individuals who release animals into the wrong habitat, unaware that their act of kindness only condemns the animal to a premature end. Andy has a post on Chinese softshell turtles being released into the sea at Labrador Park.

Needless to say, I have nothing but utter scorn and contempt for people who abandon their pets. I still have a little patience for those who release captive animals for religious reasons (i.e. fang sheng), but after several years of publicity efforts and recommendations from religious groups, I believe almost everyone should have gotten the message by now. Marcus has an excellent write-up on the harmful impacts that may result from releasing captive animals into the wild.



Releasing of Animals - Good or Bad? by the Nature Society (Singapore)

According to the Agri-Food and Veterinary Authority of Singapore (AVA), only two species of turtle can be sold in pet shops - the red-eared slider and Malayan box turtle. However, the presence of several other non-native species indicates that a significant amount of illegal trade still occurs in Singapore. In the past, when I used to visit several pet shops in Tampines and Bedok on a regular basis, I encountered various other species of turtle from time to time, from baby Chinese softshell turtles and pig-nosed softshell turtles (which used to be seen quite regularly in the past), to more exotic species like mata mata (Chelus fimbriatus) and even Indian star tortoise (Geochelone elegans). The Animal Concerns Research and Education Society (ACRES) documents their efforts in cracking down on the illegal trade in turtles as pets, while a recent paper records the availability of a wide variety of turtle species in the local pet trade.

Goh, T. Y. & O'Riordan, R. M. 2007. Are tortoises and freshwater turtles still traded illegally as pets in Singapore? Oryx, 41(1): 97-100.

Unfortunately, the problem is rampant throughout Asia; the trade in live turtles takes on horrifying proportions when one visits the animal markets of Asia, especially those in China. It is feared that the insatiable demand for turtle flesh has seriously depleted wild populations of Asian turtles and tortoises; quotas and other regulations to reduce overexploitation are routinely ignored. Rampant illegal trade at 10 to even 100 times that of the illegal trade is threatening to wipe out the Malayan box turtle in Malaysia and Indonesia. So relentless is this greed that it is now feared that the markets, having all but exhausted stocks of the Asian turtle species, are now turning their attention to North America. States like Iowa and Florida are worried about the growing threat to their turtle populations; even the more common species take time to mature and reproduce, and cannot sustain such a high level of exploitation.

The exotic pet trade also takes its toll on turtles, with tortoises from Madagascar being among the species at risk. The Roti Island snake-necked turtle (Chelodina mccordi), endemic to a single tiny Indonesian island, is critically endangered due to overcollection for the pet trade.

So lucrative is the trade in turtles and tortoises that even the Live Turtle & Tortoise Museum has been besieged time and time again by thieves, with the latest incident involving the theft of seven Indian star tortoises and three radiated tortoises (Astrochelys radiata).

It is worrying that the illegal trade in live turtles not only depletes wild populations, but also means that the risk of non-native species being introduced into vulnerable ecosystems is greatly increased. It is worth noting that trade in species like the Chinese stripe-necked turtle, pig-nosed softshell turtle, and common snapping turtle is illegal in Singapore, yet they have been recorded as being present in the wild. Hopefully, numbers of these non-native turtles are low enough to prevent breeding, but turtles can be long-lived, and it is possible that a lone individual might live for years or even decades, only to finally encounter a newly released member of the opposite sex.

Most people are aware about the threats faced by sea turtles, ranging from pollution, marine litter and nets, to poaching of adults and eggs, to loss of nesting beaches. These are threats that are also faced by a great proportion of terrestrial and aquatic turtle species, yet their plight is often overlooked in comparison with their iconic marine cousins.

Although there have been a number of recent cases where illegal trade in turtles was exposed, and the perpetrators brought to justice, clamping down on the trade requires further international collaboration, and cooperation between government agencies and NGOs. Stricter quotas need to be set and even more closely monitored, laws need to be overhauled to give endangered species the necessary level of protection, while much more needs to be done in training officials to take wildlife protection more seriously, and to detect illegally traded species.

Turtles have survived a great number of extinction events, but can they survive us?

Migration

Waders at Sungei Buloh Wetland Reserve;
(Photo by chia_alfred)

That many species of birds migrate is a fact known to most of us. But we often forget about the struggles and threats faced by many migratory birds. Habitat loss at every stage of their journey, from breeding and wintering grounds, to critical stopover and staging areas for birds to refuel and take refuge from bad weather along the way, is a great threat to most migratory bird species. Deliberate hunting and trapping is another severe challenge, especially at key points where entire flocks are funneled into a small area due to geography. Agriculture intensification, pesticide use, urban expansion, power lines, and the proliferation of wind energy and high-rise buildings can also exact a severe toll on some of the world's great travellers.

This inspiring and moving video by the Born To Travel campaign shows the amazing annual voyage undertaken by some birds, and illustrating the seemingly insurmountable challenges they face at every stage of their epic journey. That some of these birds travel great distances across entire continents, and over mountains, deserts and oceans, is simply stunning and awe-inspiring.



Although the Born To Travel campaign appears to focus on birds that utilise the African-Eurasian Flyway, it is important to note that similar migrations are to be found in other continents. For example, there are birds that travel from Canada to Argentina and back, making the trip across the Gulf of Mexico, while others travel between the Russian Arctic and India, crossing the deserts of central Asia and the Himalayas.

Singapore itself is a vital stopover for many waterbird species using the East Asian-Australasian Flyway. For much of the year, residents in our forests and wetlands are joined by a retinue of visitors from distant lands. For many birds, the loss of a single feeding and resting site can make the difference between surviving to carry on the next leg of the journey, and perishing from exhaustion.


Waders at Sungei Buloh Wetland Reserve.
Left: Whimbrel (Numenius phaeopus);
Right: Mongolian plover (Charadrius mongolus);
(Photos by kampang)

There are many books available on bird migration; recent titles include Atlas of Bird Migration, Living on the Wind, How Birds Migrate, and Bird Migration. I haven't read any of these titles myself, but I have read Silence of the Songbirds and No Way Home, which devote a fair bit of space to discussing the decline of migratory bird species.

To end off, here's a couple of trailers from a most excellent movie that is all about bird migration. Le Peuple Migrateur, also known as Winged Migration, is a 2001 film that captures the journeys of birds in amazing detail.





May these journeys continue to amaze and inspire us for generations to come.

(Hat-tip to GrrlScientist)

Disturbing to see crows feast on roadkill

STOMPer Wong spotted this group of crows feasting on the carcass of a dead cat this morning and told STOMP that the sight was disturbing.

The 20-year-old sent an MMS to STOMP just minutes after he snapped the picture at 7:45am today (Mar 24).

"This took along Bishan Street 13 and I paused to take a look because it was unusual, but at the same time, very disturbing."

Well, that's what crows do; roadkill is just another source of carrion for many scavengers, and many species of crow and raven (Corvus spp.) have learnt to forage along roads in search of food. In other countries, other scavenging birds like yellow-billed kites (Milvus aegyptius) in Africa, wedge-tailed eagles (Aquila audax) in Australia, and turkey vultures (Cathartes aura) in North America will exploit this resource, although these birds must stay alert to the dangers, so as not to become roadkill themselves.

Dawn at Bukit Batok Nature Park

A STOMPer sends in these pictures of the early morning hours, as seen through the eyes of a Bukit Batok resident.

In his email, he says:

"These pictures were taken near the Bt Batok Nature Park early in the morning before the sun rose. You can see a crescent moon slowly descending as the sun makes its appearance. It was early and there were little traffic on the road.

"At early dawn you can see the orange glow of the street lamps and the red lights on the transmitting station to warn low-flying aircraft to keep clear. You can also see the silhoutte of the trees as the birds begin their daily chorus to herald the beginning of yet another day."

Residents enjoy fishing at the Sungei Ulu Pandan park connector

Some residents were seen fishing at the park connector beside Sungei Ulu Pandan last Sunday(22 March).

A STOMPer describes the scenes he saw:

"These pictures were taken at the park connector beside Sungei Ulu Pandan near Clementi Ave 4.

"On Sunday afternoon, some residents from the nearby HDB estate came here armed with fishing rods to try their luck in fishing.

"Some anglers managed to catch some tilapia after waiting for half an hour.

"Some children also swam in the river and they seemed to enjoy themselves."

Civet cats on Tanglin Halt tree? Look again

Monday Morgue: 23rd March 2009

Jellyfish (Scyphozoa)
Cyrene Reef, 23rd May 2008

Wild Fact Sheets

Non-eels

Which one is the eel?

So far, we have looked at a wide variety of eels, from moray eels (F. Muraenidae), to snake eels (F. Ophichthidae), from conger eels (F. Congridae) and pike conger eels (F. Muraenesocidae), to the freshwater eels (F. Anguillidae). We've even spent a bit of time on 2 very little-known eel families, the spaghetti eels (F. Moringuidae) and false moray eels (F. Chlopsidae)

All the families I've talked about belong to the true eels, or Anguilliformes. In truth, there are numerous other eel-like fishes that are also known as eels, but which are not closely related to the true eels.

On our shore trips, we often encounter a long, eel-like fish. This is the carpet eel blenny (Congrogadus subducens), a predatory species commonly found in reefs, coral rubble and seagrass areas.


Carpet eel blenny, Pulau Sekudu;
(Photo by Ria)

However, the carpet eel blenny is not actually related to eels, and instead belongs to a family known as dottybacks (F. Pseudochromidae).

Other fishes on our shores which might get confused with eels include pipefish (F. Syngnathidae) and eel-tailed catfish (F. Plotosidae). However, it is easy to tell them apart from eels; pipefish have the characteristic long tubular snout, while catfish can be recognised by their barbels.


Left: ?Tidepool pipefish (Micrognathus micronotopterus), Changi;
Right: Black eel-tail catfish (Plotosus canius), Changi;
(Photos by Ria)

More rarely seen are sand-divers (F. Trichonotidae); we have not been able to identify the species encountered on the Sisters Islands.


Blue-spotted sand diver (Trichonotus setiger), Kenting;
(Photo by divingintaiwan)

Blennies (F. Blenniidae) often tend to be somewhat elongated, but the snake eel blenny (Xiphasia setifer) is the most eel-like of the family.


Snake eel blenny, Nelson Bay;
(Photo by Dave Harasti)

The cutlassfishes (F. Trichiuridae) are also quite eel-like in appearance, with the largehead hairtail (Trichiurus lepturus) being 1 of the species known to occur in our waters.


Largehead hairtail;
(Photo by Don Flescher)

In temperate waters, more eel-like fish reside. Among them are the gunnels (F. Pholidae), eelpouts (F. Zoarcidae), pricklebacks (F. Stichaeidae), wolf eels (F. Anarhichadidae), and sand lances or sand eels (F. Ammodytidae). Despite the fact that some of their common names have something to do with eels, all these fish are not closely related to eels at all.




Top: Rock gunnel (Pholis gunnellus), Zeeland;
(Photo by Arne Kuilman)
Centre left: Eelpout (Zoarces viviparus), Ona;
(Photo by andyolsson)
Centre right: Snake blenny (Lumpenus lampretaeformis), Norway;
(Photo by Erling Svensen)
Lower left: Wolf eel (Anarrhichthys ocellatus), Vancouver Island;
(Photo by Dan Hershman)
Lower right: Small sand eel (Ammodytes tobianus), Loch Torridon;
(Photo by Trevor Meyer)

The eelpouts are predominantly fish of the ocean depths, where a wide variety of elongated, serpentine fish can be found. These include the cuskeels (F. Ophidiidae), halosaurs (F. Halosauridae), deep-sea spiny eels (F. Notacanthidae), dragonfishes (F. Stomiidae), grenadiers (F. Macrouridae), bobtail snipe eels (F. Cyematidae), pelican eel (F. Eurypharyngidae), onejaws (F. Monognathidae), gulper eels (F. Saccopharyngidae), ribbonfish (F. Trachipteridae), and oarfish (F. Regalecidae). There is even a deep sea shark that looks like an eel, the frilled shark (Chlamydoselachus anguineus), which is the sole representative of its family (F. Chlamydoselachidae).

As we have seen in previous posts, several species of eel will enter freshwater. To make things more confusing, there is an unrelated family of freshwater fish known as swamp eels (F. Synbranchidae), found in tropical South and Central America, West Africa, Asia and Australia. The most well-known species is the Asian swamp eel (Monopterus albus), found throughout Asia. This species is commonly eaten, and is widespread in aquaculture; in fact, I believe that Singaporeans are generally more familiar with this species than with any of the true eels.


Asian swamp eels at Khai Seng Trading & Fish Farm, Kranji;

The spiny eels (F. Mastacembelidae) are another family of eel-like fish with representatives in South-east Asia. Native to Africa and Asia, many species can be found in the aquarium trade. Spiny eels get their name from the row of short spines on the back, in front of their dorsal fins. However, the most obvious distinguishing feature is the long fleshy appendage on the tip of the snout, which gives the spiny eel a comical appearance.


2 large species of spiny eel commonly seen in the aquarium trade.
Left: Tyre-track eel (Mastacembelus armatus);
Right: Fire eel (Mastacembelus erythrotaenia);
(Photos by cyprinoid)

Among the loaches (F. Cobitidae) of Eurasia, some species are elongated and can also bear some superficial resemblance to eels. The well-developed fins and the short barbels around the mouth should help to distinguish loaches from eels.


Left: Giant kuhli loach (Pangio myersi);
(Photo by cyprinoid)
Right: Eel loach (Pangio anguillaris);
(Photo by nttrbx)

A large fish that is commonly confused with the true eels is the electric eel (Electrophorus electricus) of South America. However, it is not an eel, and instead is a highly specialised South American knifefish.


Electric eel at Adventure Aquarium, New Jersey;
(Photo by Floater Ya-Ya)

The South American knifefishes or Gymnotiformes are freshwater species of tropical South and Central America. They generally have elongated bodies, and in fact, are are able to give off a weak electric current to help them navigate in murky waters, as well as to communicate with one another. The electric eel has gone a step further and uses electrical discharges to stun prey and defend itself. Despite their often eel-like appearance, these fish propel themselves by undulations of the long anal fin, and so do not swim like eels. The electric eel belongs to the gymnotids, or naked-back knifefishes (F. Gymnotidae), while another familiar species in aquaria, the black ghost knifefish (Apteronotus albifrons), is a member of the ghost knifefish family (F. Apteronotidae). The remaining South American knifefish families are the bluntnose knifefishes (F. Hypopomidae), sand knifefishes (F. Rhamphichthyidae), and glass knifefishes (F. Sternopygidae).




An assortment of South American knifefish.
Top left: Black ghost knifefish;
(Photo by Neil Hepworth)
Top right: Electric eel;
(Photo by brian.gratwicke)
Centre left: Banded knifefish (Gymnotus carapo);
Centre right: Bluntnose knifefish (Brachyhypopomus occidentalis);
(Photo by Miguel Landines)
Bottom left: Trumpet knifefish (Rhamphichthys rostratus);
(Photo by Ricky Mensch)
Bottom right: Glass knifefish (Eigenmannia virescens);
(Photo by Mauricio Camargo)

The featherbacks or knifefishes (F. Notopteridae) of Africa and tropical Asia are superficially similar to the South American knifefishes, but are unrelated, and lack the ability to generate electricity.


2 species of knifefish found in the aquarium trade.
Left: Clown knifefish (Chitala ornata);
(Photo by Lai Sektong)
Right: African knifefish (Xenomystus nigri);

In a bizarre example of convergent evolution, another large eel-like fish has evolved the ability to generate electricity. This is the aba (Gymnarchus niloticus), also known as the Nile knifefish. The sole member of its family (F. Gymnarchidae), the aba, a fish that is found in many African river systems, is unrelated to the South American knifefishes, but also uses a weak electrical current to navigate. Interestingly enough, in this species, it is the dorsal fin that is the main source for propulsion.


Aba;

Other African fish that can from time to time be mistaken for eels include several species of walking catfish (F. Clariidae), such as the eel catfish (Channallabes apus) and flat-head eel catfish (Gymnallabes typus). Once again, the long barbels give them away.


Left: Eel catfish;
(Photo by Benjamin Lee)
Right: Flat-head eel catfish;
(Photo by Christian Hauzar)

Two families of catfishes (F. Trichomycteridae, F. Heptapteridae) of South America have several species that are eel-like. These include species with bizarre habits, such as the infamous parasitic candiru (Vandellia cirrhosa), and the subterranean cistern catfish (Phreatobius cisternarum).


Left: Candiru;
(Photo by dylanellis30)
Right: Cistern catfish;
(Photo by Janice Muriel-Cunha)

The bichirs (F. Polypteridae) are an exclusively African family of fish that do appear eel-like in terms of appearance and habits. Predatory in nature, with long sinuous bodies, it is difficult not to draw comparisons between bichirs and freshwater eels. The elongation of the body is taken to extremes in the reedfish (Erpetoichthys calabaricus).


Left: Senegal bichir (Polypterus senegalus);
Right: Reedfish;

Befitting their prehistoric appearance, bichirs are actually among the most primitive bony fish alive today. Another family of eel-like African fish also has an ancient heritage; these are the African lungfish (F. Protopteridae). The South American lungfish (Lepidosiren paradoxa), the sole member of its family (F. Lepidosirenidae), also looks like an eel.


Left: West African lungfish (Protopterus annectens);
Right: South American lungfish;
(Photos by SRD)

Even some of the most primitive 'fish' (to use the term very loosely) are eel-like. The parasitic lampreys (F. Petromyzontidae) and scavenging hagfish (F. Myxinidae) lack jaws, and while the lamprey are included among the vertebrates, hagfish are not even considered true vertebrates; they have skulls of cartilage but lack a vertebral column.


Left: Sea lamprey (Petromyzon marinus);
Right: Atlantic hagfish (Myxine glutinosa);
(Photos by Anders Salesjö)

As if having such a great variety of eel-like fishes was not enough, there are amphibians which are also eel-like. Thankfully, there aren't any eel-like frogs; it is the caecilians and salamanders which have evolved eel-like species. The typhlonectines are a subfamily of caecilians (F. Caecilidae) which are fully aquatic, although they still breathe air. To make matters worse, they are commonly mislabeled in the pet trade as 'rubber eels'.


Rio Cauca caecilian (Typhlonectes natans);
(Photo by brian.gratwicke)

Among the salamanders, the sirens (F. Sirenidae), not to be confused with the mammals known as sea cows or sirenians, are somewhat eel-like, but have external gills and a pair of small forelimbs. The olm (Proteus anguinus) is the most eel-like member of the mudpuppy family (F. Proteidae), but can be obviously differentiated from eels by its lack of pigmentation and eyes, and the presence of bushy external gills and 4 small but well-developed legs. It is the amphiumas (F. Amphiumidae), with their elongated bodies and minuscule legs, that are most easily confused with eels. Amphiumas are sometimes known as Congo eels, although they are not eels, and don't live anywhere near the Congo Basin in Africa.



4 eel-like amphibians.
Upper left: Cayenne caecilian (Typhlonectes compressicauda);
(Photo by Danté Fenolio)
Upper right: Lesser siren (Siren intermedia);
(Photo by Pierson Hill)
Lower left: Olm;
(Photo by Nick Baker)
Lower right: Two-toed amphiuma (Amphiuma means);
(Photo by Pierson Hill)

Finally, it goes without saying that on occasion, a snake swimming in the water might be mistaken for an eel. Many snakes found in the region, such as the file snakes (F. Acrochordidae), mock vipers (F. Natricidae), water snakes (F. Homalopsidae), and sea kraits and sea snakes (F. Elapidae), are closely associated with aquatic and marine environments.




6 local species of snake which are closely associated with water.
Top left: Banded file snake (Acrochordus granulatus), Chek Jawa;
(Photo by Ria)
Top right: Painted mock viper (Psammodynastes pictus), Borneo;
(Photo by dennisikon)
Centre left: Puff-faced water snake (Homalopsis buccata), Nee Soon;
(Photo by Siyang)
Centre left: Dog-faced water snake (Cerberus rynchops), Sungei Buloh;
(Photo by Ria)
Bottom left: Yellow-lipped sea krait (Laticauda colubrina), Pulau Hantu;
(Photo by Ria)
Bottom right: Marbled sea snake (Aipysurus eydouxii), Chek Jawa;
(Photo by Ng Bee Choo)

Oh, and do you remember the 2 fish at the top of this post? Which one is the eel? Well, here's the answer...


Brown-spotted moray (Gymnothorax reevesii), Beting Bronok;
(Photo by Chee Kong)


Carpet eel blenny, Sentosa;

And with that, I've come to the end of my eel series.

Part 1: Moray eels (Muraenidae)
Part 2: Snake eels (Ophichthidae)
Part 3: Conger eels (Congridae) and Pike conger eels (Muraenesocidae)
Part 4: Freshwater eels (Anguillidae)
Part 5: Spaghetti eels (Moringuidae) and false moray eels (Chlopsidae)
Part 6: Non-eels (this post)