Species Profile: Icebreaker

Walks on the beach are a great way to discover marine life. The remains of creatures from all over the sea wash up on the shore. Often these remains are just skeletons or shells, but sometimes whole bodies will wash up. Mostly those of small fish, cephalopods and jellyfish, but every now and then, the sea reveals its treasures when it drops a massive carcass on the beach.

On one of Team Schoedsack’s excursions to the shore they encountered something we didn’t expect. As they walked down the beach, they saw something in the distance that looked like a large rock. Strange was it, to see such a large rock on a nearly completely flat beach. As they came closer, they saw that it was hollow. It was no rock at all. Rather it was a skull, nearly 8 meters in length, it was largest skull of any animal encountered in Dome 5 so far. Way too heavy to move, the sand around it was dug away to inspect closer. It had a massive horn on the tip of its snout, two very large serrated spikes sticking out from the ventral side of the skull and on the top, there was a sharp keel running all the way from the snout to the back of the thoracic plates. While the rest of the body was missing, the plates led us to assume this creature must’ve been a placoderm.

It was not until winter that year, that finally a glimpse was caught of the animal that the skull belonged to. Early in the morning, the whole camp was scared awake when, out of nowhere, they heard a cracking noise almost as loud as a gunshots, again minutes later. Less loud cracks followed for the next half an hour. It was determined that the sounds came from the coast, so they went investigating. Most of them thought it was probably a glacier, collapsing in the water, but some speculated it was an animal that made this sound.

As the shore was approached, they saw the sea ice had been broken, but not in any way a glacier could have done. Far from the snow covered beach, were huge holes in the ice, connected by lines of open water. Then, just as the team was about to depart, they saw it in the distance. A massive arrow-shaped creature jumped out of the water and broke the sea ice as it fell down. Before pictures could be taken or sketches made, it was gone. They stayed for nearly 3 hours after that, but it never returned. Whatever it was, it became a fascination for all teams, and all winter long we were wondering and pondering over the mysterious “icebreaker”.

In early summer, when all the sea ice had finally melted away, they were finally able to take the boat out and do some marine observation. It appeared so, that in this part of Dome 5, the sea is quite deep and sadly there was no luck to be had finding benthic species. They did however discover a variety of small fish and some small cephalopods that behaved as if they were krill. Of all the fish encountered, the most populous variaty was a small osteostracan filterfeeder. Because of the upturned epimera of its head plate resembling pointy ears, it was dubbed the elf fish. Though, like their ancestors, elf fish lack jaws, they make up for it with hard griding plates in their throats, and a radula-like tongue.

Suddenly they were disturbed by the sonar detecting a large entity approaching. When, after an anxious wait it did finally appear, everyone was as amazed as they were confused. Measuring over 16 meters long, this animal was by far the largest encountered so far in the dome, and something about it just did not look right. Its large body was topped by an armour plated head, with two very large pectoral fins and was propelled forward by a deeply keeled, downturned heterocercal tail, but it also clearly had gills. It matched both the skull on the beach and the glimpse they saw during winter perfectly. They had found the Icebreaker and it was stranger than any of us could ever have imagined.

The icebreaker is a petalichthyid placoderm descendant that grows over 16 meters long. It is a filter feeder, eating only plankton and small fish. The most curious aspect of its biology, is the fact that it swims upside down, like some crustaceans do on Earth. This is possibly an adaptation to the behaviour through which it earned its name. By jumping out of the water at full speed and breaking the ice with its sharply keeled head and dorsal plates. The serrated spines in front of the pectoral fins are also used to break thinner sea ice and possibly play a role in mating. Why exactly it’s so adapted to break ice is not yet fully understood, but it might be to stay close to its surface swimming food. Whatever the reason they do it, they play an important role in the marine ecosystem and are considered a keystone species due to their impact. Not only do they allow their own food to proliferate in winter, by breaking the ice they expose dark open water which, in turn absorbs more heat causing the seas to stay warmer and more fruitful than they would be normally.

This illustration, as well as the accompanying text were a fan-submission by DemonicManchot from DeviantArt, best known for his flattacanth project. If you have similar fan-contributions in mind, you can send them to us and we might include them if we consider them fitting for the world.

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