|Cowichan Lake Lamprey|
Lampreys are an amazing group of ancient fish species which first appeared around 360 million years ago. This means they evolved millions of years before the dinosaurs roamed the earth. There are about 39 species of lamprey currently described plus some additional landlocked populations and varieties.
In general, lamprey are one of three different life history types and are a combination of non-parasitic and parasitic species. Non-parasitic lamprey feed on organic material and detritus in the water column. Parasitic lamprey attach to other fish species to feed on their blood and tissues. This is why lamprey are often unfairly called “aquatic vampires”.
Most, 22 of the 39 species, are non-parasitic and spend their entire lives in freshwater. The remainder are either parasitic spending their whole life in freshwater or, parasitic and anadromous. Anadromous parasitic lampreys grow in freshwater before migrating to the sea where they feed parasitically and then migrate back to freshwater to spawn.
The Cowichan Lake lamprey (Entosphenus macrostomus) is a freshwater parasitic lamprey species. It has a worm or eel-like shape with two distinct dorsal fins and a small tail. It is a slender fish reaching a maximum length of about 273mm. When they are getting ready to spawn they shrink in length and their dorsal fins overlap.
Unlike many other fish species, when lampreys are getting ready to spawn you can tell the difference between males and females. Females develop fleshy folds on either side of their cloaca and an upturned tail. The males have a downturned tail and no fleshy folds. Lamprey don’t have gills like other fish species but have pores for breathing. These seven gill pores are located one after another behind the eye.
There are several characteristics which are normally used to identify lamprey. Many of these are based on morphometrics or measurements, of or between various body parts like width of the eye or, distance between the eye and the snout. Other identifying characteristics include body colour and the number and type of teeth.
Some distinguishing characteristics of this species are the large mouth, called and oral disc and a large eye. This species also has unique dentition. For example, these teeth are called inner laterals. Each lateral tooth has cusps and together they always occur in a 2-3-3-2 cusp pattern.