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The earliest lamprey with the specialised toothed oral disc typical of modern lampreys is Yanliaomyzon from the Middle Jurassic of China around 163 million years old, which is thought to have had a predatory lifestyle like modern lampreys, and probably had a three stage life cycle including ammocoetes. [6]
Larvae of all lampreys are called ammocoetes and when small ABL ammocoetes have a dark band running longitudinally along the body, a dark head region, and the remainder of the body is clear. As they increase in size the body becomes increasing darker, reaching a dark brown by the time the ammocoetes reach their maximum size of about 250 mm (10 in).
The Pacific lamprey (Entosphenus tridentatus) is an anadromous parasitic lamprey from the Pacific Coast of North America and Asia in an area called the Pacific Rim. [4] It is a member of the Petromyzontidae family. The Pacific lamprey is also known as the three-tooth lamprey and tridentate lamprey. Ammocoetes held by biologist in the Carmel River
The western brook lamprey and river lamprey have been considered a clade separate from the other western U.S. lamprey species. [12] However, more recent genetic research suggests the western brook lamprey would be better categorized as a member of a Lampetra ayresii species complex. [ 11 ]
As with all lamprey species, the least brook lamprey spends the majority of its life as a worm-like ammocoete. The ammocoete (5 mm–20 cm) is clear with a pigmented head when small (<5 cm), but becomes a dark/golden brown as it matures. Ammocoetes have pigmented eye spots located in the head that can detect light and dark.
This lamprey is usually about 13 to 32 centimetres (5.1 to 12.6 in) long, but specimens have been known to reach 63 centimetres (25 in) and 200 grams (7.1 oz) in weight. Non-anadromous individuals are rarely over 18 centimetres (7.1 in) long. [4] It is brown, gray, or olive in color with a paler belly. There are two dorsal fins located near the ...
Amniotes have the ability to procreate without water bodies. Because the amnion and the fluid it secretes shields the embryo from environmental fluctuations, amniotes can reproduce on dry land by either laying shelled eggs (reptiles, birds and monotremes ) or nurturing fertilized eggs within the mother ( marsupial and placental mammals ).
The silver lamprey is an eel-like fish with an attenuate body composed of 49–52 clearly defined segments (i.e. myomeres, between the last gill slit and the anus).Silver lampreys possess a cartilaginous skeleton, and adults generally grow to a length of 12 inches and are silvery or bluish in color when spawning.