I saw this and could think of nothing but the alien from the movie Predator.
This is a frontal view of the head of a male Branchinecta brushi. This species of fairy shrimp is interesting in several ways. First, it is a species new to science, having just been described in a paper last week.
Second, this is one of the two highest crustacean species on the planet. There is one other crustacean found in the same pools that B. brushi is found in.
I also have to give this paper credit for the best opening line for a Materials and Methods section I may have ever read:
Dr. Charles F. Brush collected our specimens on 13 December 1988 during a successful bid to break the world record for high altitude SCUBA diving.
And yes, the species was named after the record holder who discovered and collected them.
The location of this successful world record bid was Cerro Paniri, a mountain in Chile. This image of the crater pond where this species was found gives a sense of what you have to do to break a world record in altitude, either for SCUBA or finding new species:
That’s 5,946 metres above sea level. This means crustaceans in these kinds of environments tend to have eggs that encyst, and can remain dormant for long periods until water returns, or be taken up and dispersed by birds. That this is particular species reproduces sexually also suggests that several cysts were introduced to the area by birds.
What’s slightly nerve wracking is that, as you can imagine, pools like this tend to come and go. This particular species is known only from the one collection in the one pool, and the authors suggest it might have evolved and speciated only in that pool. That makes it a good thing that it’s so high up, humans are unlikely to mess with it.
Hegna, T., & Lazo-Wasem, E. (2010). Branchinecta brushi n. sp. (Branchiopoda: Anostraca: Branchinectidae) from a Volcanic Crater in Northern Chile (Antofagasta Province): A New Altitude Record for Crustaceans Journal of Crustacean Biology 30(3): 445-464 DOI: 10.1651/09-3236.1