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Batrachogymnotus - Neocene Project

By electreel
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Batrachogymnotus (Batrachogymnotus rivularis)
Order: Tailless amphibians (Anura)
Family: New Zealand false salamanders (Virilogyrinidae)
Habitat: New Zealand (Northern Island), the flatland parts of rivers overgrown with aquatic plants.
Having evolved in conditions of island isolation and at almost full absence of competitors, New Zealand false salamanders became the original analogues of tailed amphibians of Northern hemisphere. Among them species of various sizes appeared, similar to tailed amphibians in various degrees. The most progressive species had almost completely lost the similarity to tadpole, and the most primitive species, which inhabit the rivers of islands, keep completely larval shape. To such species batrachogymnotus living in subtropical climate of Northern Island belongs; it is a large species of New Zealand false salamanders. It never creeps to land and constantly lives in water among thickets of underwater plants.
This creature is a long-bodied species of eel-like shape, reaching the length of 80 – 90 cm, and sometimes up to 100 cm; males are larger than females, but are more graceful than fems are. Body and head are short, and tail makes more than 3/4 of general length of animal. It is muscled and rather deep, bordered with leathery fin plica. On the top part of body and tail fin is reduced in great degree and represents only low skin elevation. But the bottom part of tail fin is wide; the fin is stretched along the belly side of body up to cloacal aperture. Batrachogymnotus swims with the help of wavy movements of the bottom part of tail fin. It this feature it is very similar to South American gymnotid fishes and demonstrates, thus, a vivid example of convergence. Such manner of swimming is connected to features of habitat of animal: batrachogymnotus lives in dense thickets of plants where it is difficult to turn around. Like gymnotid fishes it can easily swim back to front, hiding among plants from predators or competitors.
Limbs of batrachogymnotus are rather short, forward paws are much shorter than rear ones. At 30 – 40% of representatives of population forward limbs may not develop at all. Hind legs lack membranes between toes and can be used at movement among plants. Hip joint in them is very mobile, and paw can be turned forward, grasping stalks and leaves of plants by toes.
Head of this amphibian is flat, with well advanced eyes located on its edges. Mouth of animal is wide, capable to be stretched vastly and swallow large prey. In corners of mouth long sensitive wattles grow, supplied with chemoreceptors.
Colouring easily permits batrachogymnotus to hide among plants and stones. The basic background of colouring is yellowish-brown, on it there are are randomly scattered spots of dark brown and black color, forming a marble pattern. Stomach is almost white with separate black specks.
Batrachogymnotus is an active ambush predator. It feeds on fishes and crustaceans, eats frogs and other small vertebrates, and also aquatic larvae of insects. At swallowing of large prey stomach and belly wall of animal can stretch greatly; animal easily swallows fishes in length up to third of own length of the hunter. For the significant part of time batrachogymnotuses hide in thickets of water plants and in driftwood. These animals behave aggressively to each other, and fight is fastened between them at their meeting. Usually animals mark borders of the territory, rubbing body against underwater objects.
Spawning at this amphibian takes place in spring. When it is raining in mountains, the rivers overflow banks and water is considerably enriched in oxygen. It is a stimulus for the beginning of courtship behaviour at these animals. Males turn brighter – their throat reddens, and on sides distinct dark vertical strips appear. Male’s skin turns lighter, and the back becomes almost white. The female gets black colouring with white stomach. Male courts the female, swimming around her and displaying striped colouring of sides. He “leads” the female to rich thickets of plants or to driftwood and trees fallen in water. Here both parents clear a site of bottom of dust with the help of lips, and then female spawns eggs directly on the ground. Among small-leaved plants adult individuals arrange a kind of nest, whirling among stalks and trampling them down. The female spawns large eggs – up to 100 – 150 pea-sized grains of roe. Male fertilizes clutch and at once banishes the female. He protects eggs, pasting them to his own stomach and fin. First minutes after spawning eggs gets glutinosity and male at once lay on them. Eggs stick to his skin and does not come unstuck even at sharp movements. Protecting eggs, male becomes very cautious; he hides in shelters and eats almost of nothing, except for small larvae casually coming almost right up to him. For batrachogymnotus the care of posterity of first weeks after hatching is very characteristic. Male carefully protects school of tadpoles, and they keep near to the parent. Tadpoles in first of all remember his smell, but later begin to react to his appearance and movements. Male drives predators away from them and digs bottom in searches of small invertebrates. The young ones leave male at length of 2 – 3 cm. Back legs start to grow at them at the age of about half-year, at length about 15 cm. At the age of 2 – 2.5 years young individuals become capable to breeding. Life expectancy of batrachogymnotus may reach 20 years.

The idea about existence of this group of animals was proposed bt Timothy Morris, Adelaide, Australia.
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Comments10
anonymous's avatar
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PeteriDish's avatar
I LOVE the idea! Fantastic!
electreel's avatar
Thank you! I love the idea of salamander-looking anurans too =D
PeteriDish's avatar
You're welcome!
indigomagpie's avatar
Hey, that's really clever! Do the limbs have any use?
Amplion's avatar
I meant I agree with the above. My English is so bad: D
Amplion's avatar
Join us, image is very beautiful!
electreel's avatar
I have joined long time ago =D
AlexSone's avatar
Great! Your illustrations are better and better!
electreel's avatar
anonymous's avatar
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