Criodrilidae
Encyclopedia
The family Criodrilidae is represented by genera Criodrilus and Biwadrilus that are limicolous (mud-dwelling) and/or aquatic earthworm
s endemic to the Palaearctic currently known only from Europe and Japan, respectively. Only 3 or 4 species are described and the type, Criodrilus lacuum has been introduced into the Americas (North and South) and is found rarely in plant pots or paddy fields.
Criodrilidae member species are characterised by holoic nephridia absent from anterior segments (cf. Pontodrilus), a simple gut with no gizzard
and no typhlosole
. They are true earthworms, having a complex vascular system with capillaries, the male pores (on 15 or 13) behind the female pores (on 14) and a multi-celled clitellum
. They were at one time placed in the earthworm families Glossoscolecidae
or Almidae
but at present are considered to constitute their own family.
Criodrilidae species (criodrilids) are found in mud next to lakes and waterways (cf. North American Sparganophilus). They feed in the low oxygen mud and organic material, but with their highly vascularized posterior region on or near the surface.
Criodrilus has no accepted common name; Biwadrilus is the Lake Biwa
earthworm.
Earthworm
Earthworm is the common name for the largest members of Oligochaeta in the phylum Annelida. In classical systems they were placed in the order Opisthopora, on the basis of the male pores opening posterior to the female pores, even though the internal male segments are anterior to the female...
s endemic to the Palaearctic currently known only from Europe and Japan, respectively. Only 3 or 4 species are described and the type, Criodrilus lacuum has been introduced into the Americas (North and South) and is found rarely in plant pots or paddy fields.
Criodrilidae member species are characterised by holoic nephridia absent from anterior segments (cf. Pontodrilus), a simple gut with no gizzard
Gizzard
The gizzard, also referred to as the ventriculus, gastric mill, and gigerium, is an organ found in the digestive tract of some animals, including birds, reptiles, earthworms and some fish. This specialized stomach constructed of thick, muscular walls is used for grinding up food; often rocks are...
and no typhlosole
Typhlosole
A typhlosole is an internal fold of the intestine or intestine inner wall. Typhlosoles occur in bivalve mollusks, lampreys and some annelids and echinoderms....
. They are true earthworms, having a complex vascular system with capillaries, the male pores (on 15 or 13) behind the female pores (on 14) and a multi-celled clitellum
Clitellum
The clitellum is a thickened glandular section of the body wall in earthworms and leeches, that secretes a viscid sac in which the eggs are deposited...
. They were at one time placed in the earthworm families Glossoscolecidae
Glossoscolecidae
Glossoscolecidae is a large family of earthworms which has native representatives in South and Central America. The species Pontoscolex corethrurus has a circumtropical distribution....
or Almidae
Almidae
The animal family Almidae includes about six genera of segmented worms.A notable peculiarity of some species in this family is a tendency to extensions of the body wall in the vicinity of or including the male pores. These extensions may be mere protuberances, as in some species of Drilocrius; or...
but at present are considered to constitute their own family.
Criodrilidae species (criodrilids) are found in mud next to lakes and waterways (cf. North American Sparganophilus). They feed in the low oxygen mud and organic material, but with their highly vascularized posterior region on or near the surface.
Criodrilus has no accepted common name; Biwadrilus is the Lake Biwa
Lake Biwa
is the largest freshwater lake in Japan, located in Shiga Prefecture , northeast of the former capital city of Kyoto. Because of its proximity to the ancient capital, references to Lake Biwa appear frequently in Japanese literature, particularly in poetry and in historical accounts of battles.-...
earthworm.