How to Identify Lamprey

To identify Lamprey (Petromyzontiformes), look at these key features.

Physical Characteristics

Body shape

eel-like

Coloration

Dorsal coloration typically dark grey, olive, or brown, fading to lighter grey or white ventrally. Some species may have mottled patterns. Coloration can vary with habitat and life stage.

Scale type

none

Mouth position

terminal

Distinctive features

Jawless, funnel-like sucking mouth with horny teeth, Seven external gill openings (pores) on each side of the head, Scaleless, smooth, slimy skin, Single nostril on top of the head, Absence of paired fins (pectoral and pelvic fins)

Dorsal fin

Typically two distinct dorsal fins, sometimes confluent, located posteriorly on the back.

Tail fin

Caudal fin is diphycercal (vertebral column extends to the tip of the tail, dividing the fin into two equal lobes), often continuous with the posterior dorsal fin.

Pectoral fin

Absent

Distinctive fins

Absence of paired fins (pectoral and pelvic fins) is a key distinguishing feature of lampreys.

Identification Tips

1. 1

   Mouth

   Look for the distinctive circular, jawless sucking disc armed with numerous horny teeth. This is the most defining feature.

2. 2

   Gill Openings

   Count the seven small, round gill openings (pores) arranged in a line on each side of the head, posterior to the eye.

3. 3

   Fins

   Note the absence of paired fins (pectoral and pelvic fins). They possess two dorsal fins and a caudal fin that is often continuous with the posterior dorsal fin.

4. 4

   Skin

   Observe the smooth, scaleless, and often slimy skin, which is characteristic of lampreys.

5. 5

   Body Shape

   Their elongated, eel-like body is a general indicator, though other fish (e.g., true eels) also share this shape.

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