Order

Petromyzontiformes

  Class

Petromyzonti

No. in FishBase

Genera : 1 | Species : 3 Eschmeyer's Catalog of Fishes

  Environment

Fresh : Yes | Brackish : Yes | Marine : Yes

  Division

Peripheral/diadromous

  Aquarium

none

  First Fossil Record

     

  Remark

Monogeneric family.
Distribution: South-East Australia (2 spp.) and Chile (1 sp.).
Size; larvae (ammocoete) max 16 cm, adults max 54 cm.
Habitat and ecology: Marine species anadromous. Parasitic or non-parasitic, the latter restricted to freshwater. One species pair, with one species parasitic, and the other non-parasitic.
The larval (ammocoete) stage is filter feeding, whereas the adult uses the sucker shaped mouth to attach to other fishes and feeds off the wound.
Description: Jawless vertebrates with cartilaginous skeleton and notochord. Eel-like in shape; scales and paired fins absent; 2 dorsal fins; second dorsal fin confluent with caudal fin in ammocoetes; adults with well developed eyes; pouch-like gills not supported by gill arches; corneous teeth on the circular oral disk and the tongue; oral papillae absent from the anterior as well as the posterior edges of the oral disc, but present along the lateral edges; all oral papillae of uniform size; oral fimbriae absent; 2 triangular and tricuspid supraoral laminae; the multicuspid radial plates found in the anterior, lateral and posterior fields of the oral disc in prespawning (immature) adults break down and leave only individual unicuspid teeth in spawning (mature) adults; labial teeth pointed; transverse lingual lamina w-shaped in prespawning individuals; dorsal and ventral nerve roots separated; nasohypophyseal sac has an external opening only; 3 buccal glands; eyes dorsolateral in immature adults and dorsal in mature adults; intestinal tract with spiral valve and cilia; cloaca under the posterior half of the second dorsal fin in ammocoetes and adults.
Reproduction: Sexes separate; eggs numerous (thousands), small and not yolky, buried in spawning redds excavated in clean, hard bottoms (litophilous broodhiders). Non-parasitic species breed immediately after metamorphosis. Parents die after spawning. The larval (ammocoetes) stage lives for several years in freshwater before undergoing a radical metamorphosis and then as a rule returns to the sea.
Lampreys (together with hagfishes) are the most basal extant vertebrates. Definite fossil records date back to the upper Carboniferous, about 280 million years ago (Ref. 12268). Also, from the Cretaceous of China ,125 million years ago and from the Devonian of South Africa, 360 million years ago (Ref. 89241).
Ammocoetes and adults are used as bait in some areas. A number of species are used as food.
Classification: Previously a subfamily of Petromyzontidae.

  Etymology

  Reproductive guild

  Typical activity level

  Main Ref.

Renaud, C.B. 2011

  Coordinator

  Deep Fin Classification