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Today on Animal Fact Files, we’re talking about krill. We have a whale of a time here, don’t forget to subscribe! Most people have heard of krill, but what exactly are these tiny little creatures? Krill are marine planktonic crustaceans who kind of look like baby shrimp, though they aren’t. There are currently just over 80 recognized species of krill and they can be found in all the world’s oceans. Different species have difference preferences on where they live. Some, like the antarctic krill, like it cold and are generally found in polar regions, while others may be found floating close to the equator. Krill are some of the largest zooplankton living in our oceans, with some species reaching more than two inches (5 centimeters) in length. That’s like the length of a paper clip! Some species drift in the open ocean, while others are found on coastal shelves. Some live in deep water, while others stick closer to the surface, and many species actually undergo migrations in search of food. During the day, many krill species will sink lower in the water column. At night, they rise closer to the water’s surface and feed. Being tiny themselves, krill eat some pretty small meals. They generally dine on phytoplankton, copepods, fish eggs and larvae, detritus, and algae. Ice algae can be a main staple in the diets of some krill species, so these depend on ice formations in order to meet their dietary needs. Krill in turn are eaten by… well basically everything in the ocean. Maybe not everything everything, but animals from penguins, to seals, to fish, to the largest animals living on our planet, the whales, depend on krill in order in survive. So, even though they might seem insignificant, krill are one of the foundational aspects of the oceanic food web.

Krill are found in groups called swarms. In one cubic meter of water (35 cubic feet) there can be an average of 10,000 individual krill. To put that into perspective that would be like having 3,000 individual krill swimming around in your bathtub. And that’s just one part of the krill swarm. A swarm of krill may only be a dozen or two feet long, but some swarms can go on for miles! That amounts to a lot of krill - which is perfect for animals like blue whales who during some parts of the year need to eat 4 tons of krill per day! And I thought Chester loved food!

Being in a group can make finding a mate much easier, too. Some species of krill biolumence - this may be a means of communication such as letting all the other krill around know that there’s a hungry whale nearby, or it could also be a means of attracting a mate. Male krill will seek out a female who he’ll basically hug until it’s time to part ways. The female may either release her fertilized eggs to sink towards the bottom of the ocean, or she may hold onto them until they’re ready to hatch. Usually the ones that release their eggs have more eggs at a time, while the ones that hold onto their eggs have fewer. Once they hatch, krill undergo a few life stages, molting as they grow until they reach adulthood. In Antarctic krill specifically it takes about ten days for the released eggs to hatch and about ten days between each larval stage, but this is just one example of how these diverse creatures develop. Some species may live less than a year, while others can live to be five or older!

For more facts on krill, check out the links in the description. Give a thumbs up if you learned something new today, and thank you for watching Animal Fact Files.