Family Petromyzontidae

by. Nolvyhindarto,S.Si_Encartablog_Animals

Lampreys

Selected Characters: Elongate, cylindrical shape; no jaws;
disc-shaped mouth lined with keratinized 'teeth'; seven porelike gill
openings; well-developed eyes; no paired fins.

class="Normal_0020_0028Web_0029__Char" style=" text-decoration: none">This family of primitive jawless vertebrates is found in cool areas
of the world. Lampreys live in freshwater or are anadromous; none are
strictly marine. After hatching in freshwater, larval lampreys,
called ammocoetes, burrow into the river bottom and filter nutrients
from the substrate. While buried in the mud, ammocoetes undergo metamorphosis
to the adult lamprey form, after which they emerge. Some lampreys then
go through a parasitic phase, when they use the disc-shaped mouth lined
with hard tubercles to attach to the body of a fish, rasp a wound in
the skin, and feed on body fluids. In other lamprey species, the digestive
system degenerates shortly after metamorphosis and the adult does not
feed, but reproduces right away and dies shortly thereafter. These nonparasitic
lampreys live exclusively in freshwater, while parasitic lampreys may
be either freshwater or anadromous. North American lampreys have diploid
chromosome numbers of 164 to 168 or more, the largest chromosome number
of any group of vertebrates. There are 41 living species of lamprey.
Two lamprey species can be found in Puget Sound, both of which are parasitic.
Our largest lampreys grow to a maximum of 76 cm. Lampreys are moderately
common in some areas of Puget Sound.

Species

Lampetra tridentata Pacific Lamprey

Lampetra ayresii River Lamprey

Retrieved from:” http://www.washington.edu/burkemuseum/collections/ichthyology”