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[34] [36] The glossiphoniids brood their eggs, either by attaching the cocoon to the substrate and covering it with their ventral surface, or by securing the cocoon to their ventral surface, and even carrying the newly hatched young to their first meal. [37] When breeding, most marine leeches leave their hosts and become free-living in estuaries.
In the English Channel, small common sole may have one or two leeches on them while large fish may have forty or more of the parasites. [2] Adult leeches attached to the underside of fish lay eggs on the seabed in locations where the fish like to semi-bury themselves in the sediment; the eggs have stalks and are anchored to grains of sand.
Glossiphoniid leeches exhibit remarkable parental care, the most highly developed one among the known annelids. They produce a membranous bag to hold the eggs, which is carried on the underside. The young attach to the parent's belly after hatching and are thus ferried to their first meal. [6] Certain Glossiphoniidae parasitize amphibian species.
Ozobranchus branchiatus are known to complete their entire life cycle on host turtles, which is an unusual trait shared only by a few other species of leeches. This is accomplished by laying eggs on the turtle and attaching them with a cementing substance. The eggs will hatch and attach to the host turtle. [4]
Leeches are hermaphrodites, and mating may take place on or off the fish host, but in either case, the cocoon, usually containing a single egg, is deposited elsewhere, usually stuck to a stone or piece of vegetation, or even to the carapace of a crustacean. When the egg hatches, the juvenile leech has about a week to find a suitable fish host ...
The clitellum is part of the reproductive system of clitellates, a subgroup of annelids which contains oligochaetes (earthworms) and hirudineans (leeches). The clitellum is a thick, saddle-like ring found in the epidermis (skin) of the worm, usually with a light-colored pigment. To form a cocoon for its eggs, the clitellum secretes a viscous ...
Earthworms store their partners' sperm in spermathecae ("sperm stores") and then the clitellum produces a cocoon that collects ova from the ovaries and then sperm from the spermathecae. Fertilization and development of earthworm eggs takes place in the cocoon. Leeches' eggs are fertilized in the ovaries, and then transferred to the cocoon.
As in other species of leech, a cocoon is secreted by the clitellum, a thickened glandular section of the body wall behind the head, and this moves forwards over the head, receiving fertilised eggs from the gonopore on the way. [5] In some areas, Erpobdella obscura has a semelparous life history, i.e., the leech dies after reproduction.