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Wednesday, June 28, 2006

ANIMAL TRACKER

Eight-barbel loach


* Japanese name: Hotoke-dojo
* Scientific name: Lefua echigonia
* Description: Loaches are in the family of ray-finned fish. They have a flattened body, and four pairs of sensory organs, known as barbels, around the mouth, like whiskers. Catfish have similar sensory organs, but belong to a different family. Loaches don't have scales. The body is light brown, with darker brown spots. They are small fish; males grow to up to 6 cm, females to 7 cm.
* Where to find them: On the beds of rivers in Honshu and Kyushu. They prefer fast-flowing water. Eight-barbel loaches are capable of reproducing rapidly and establishing a good population size, but habitat changes have made them much rarer than in the past.
* Food: These loaches are scavengers, which is why they live on the bottom of rivers. The mouth opens downwards, making it easier for the fish to feed on pretty much anything they detect with their barbels -- whether bits of dead plants and animals, insect larvae or other invertebrates such as crustaceans.
* Special features: When the water temperature warms to 14 to 16 degrees, the fish are ready to spawn. A male patrols a territorial zone on the bottom of the river, swimming rapidly along the length of his territory, while a female swims up and down near him. After some time doing this, the female suddenly attempts to dive into the floor, propelling herself into the sand or under a stone. This is the signal the male has been waiting for, and he nibbles and pecks at her back and tail. The female then beats her fins harder in her attempt to burrow into the sand, and when she has succeeded, or found cover under a stone, followed closely by the male, she starts trembling and releases her eggs. The male releases his sperm over them. That's it. Both fish swim out of the hole. The next day, they can do it again, and females can lay up to 14 batches of eggs in this way. As might be expected, as the number of batches a female lays goes up, so does the rest time required between each spawning. Bigger females lay bigger eggs, which explains why the females of this species are bigger than the males. Hotoke, incidentally, means "Buddha," and although this fish at first sight doesn't seem particularly enlightened, perhaps its whiskers have earned it the name.

PHOTO COURTESY OF BIO-IMAGE NET



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