Water magazine No. 19 Anomalocaris

Anomalocaris lived 520-535 million years ago. It is one of the largest predators of the Cambrian, reaching a length of up to 38 cm. Previously, it was believed that it grew up to 1 meter in length, but this estimate seems unlikely due to the ratio of the length of the appendages to the body. On the sides of the body, anomalocaris had blades resembling the parapodia of annelids, with which it actively swam, making undulating movements. The blades were paired: one was located at the top, the other was at the bottom and slightly shifted back, overlapping the nearest blades. This allowed them to act as one big fin. There was a large, fan-shaped tail. Using a controlled model, it was proved that this type of swimming is quite stable, which is why the anomalocaris did not need a developed brain to maintain balance during swimming. The mouth of radiodonts has an unusual structure. Such an oral apparatus is not found in any of the modern and extinct representatives of the arthropod type. The oral cone of anomalocaris was disc-shaped and consisted of several plates. The mouth opening of the anomalocaris resembled a pineapple and had several rows of teeth. The hole could shrink, but there was always a gap of about 5 mm in diameter. In some large individuals, it reached up to a centimeter. In front of the mouth cone was a pair of frontal appendages, reaching a length of up to 18 cm. The frontal appendages of the anomalocaris consisted of 14 podomers, almost each of them carrying a sharp thorn-endite.

Judging by the findings from the Emu Bay shale, the eyes of anomalocaris A. cf. canadensis were the most powerful among invertebrates. They were 30 times more powerful than the eyes of trilobites, which were previously thought to have the most powerful eyes. Anomalocaris had 16 thousand lenses in the eye, providing a resolution of 3 cm.  

For a long time, it was believed that anomalocaris was one of the oldest predators that hunted trilobites. The structure of the oral cone and the preserved intestinal glands suggest this idea. However, its ability to chew through shells has been questioned.The lack of wear on the oral cones of anomalocaris suggests that they rarely came into contact with the hard shells of trilobites. Rather, they were used to feed soft-bodied organisms by suction, otherwise the cone would have broken. According to one version, anomalocaris grabbed its prey by the back end of the body with its appendages and swung it from side to side. This would cause stress damage in the weak points of the cuticle, which could cause it to rupture, and the predator could gain access to the soft contents of the victim. This hypothesis suggests that in this way anomalocaris exerted evolutionary pressure on trilobites, providing them with the opportunity to collapse in the future.

Anomalocaris is part of the large Burgess shale complex, as well as a number of other invertebrate complexes in China and Australia.