Haikouichthys

Haikouichthys

Haikouichthys is quite a mouthful to say for such a tiny creature. (High-Koo-ICK-Thisss!) These prehistoric swimmers measured only about an inch long, and lived way back in the Early Cambrian around 530 million years ago!

Haikouichthys is one of the many, many animals that evolved during the Cambrian. This period, which lasted from 542-488 million years ago, saw rapid and diverse evolution and population growth. What makes this particular animal so interesting is that it could be considered one of the very first fish. They had skulls, designating them as some of the earliest craniates. However, the fossil record is unclear as to whether they had actual spines, or just primitive notochords.

Spine or not, Haikouichthys demonstrated several other traits that can be found in modern fish. They had relatively fish like shapes, complete with two eyes and a mouth at the front of their heads, fines, and bilateral symmetry.

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Status : Lived 530 million years ago
Location : Fossils found in China
Size : Length 1in (2.5cm)

Classification : Phylum : Chordata -- Superclass : Agnatha -- Family : Myllokunmingiidae
Genus : Haikouichthys

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Sea Lamprey

Sea Lamprey Mouth

Phylum : Chordata
Class : Cephalaspidomorphi
Order : Petromyzontiformes
Family : Petromyzontidae
Genus : Petromyzon
Species : marinus

Length : 20in (50cm)

IUCN Status : Least Concern

Despite the name, the Sea Lamprey can be found in freshwater areas as well as the sea. They are a parasitic species located in and around the Atlantic Ocean, the Mediterranean Sea, and the American Great Lakes. Some Sea Lampreys spawn in freshwater, but some have made the Great Lakes their home, moving in permanently as invasive species.

Sea Lamprey attached to Lake Trout

The Sea Lamprey is a primitive, cartilaginous fish with an eel-like body. They have circular mouths filled with sharp teeth that they use to latch on to their hosts bodies. The Lamprey saliva also possesses and anticoagulant that makes it very difficult for their host's wound to heal. They allows the Lamprey to feed for much longer. If the host doesn't die first, the Lamprey can stay attached for weeks at a time. Lampreys target many different species, and have few, if any, natural predators.

A few measures have been taken to control the Lampreys in the Great Lakes. One is lampricide, a chemical that kills Lamprey larvae but that has little affect on other fish species. Barriers and sterilization have also helped to reduce the numbers. Lamprey populations in Lake Michigan have reduced by 90% thanks to these tireless efforts.

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