A Colorful Amphipod with a Big Snoot - Observation of the Week, 12/21/21

Our Observation of the Week is this Thorlaksonius platypus amphipod, seen in the United States by @imlichentoday!

[Siena McKim (@imlichentoday) wrote a wonderful piece this week that flowed really well so here it is in full. I’ve added some links to the text and made some minor copy edits, but otherwise everything between here and the line break is what Siena wrote. Enjoy! - Tony]

My earliest memory of nature was when I sucked on a dried slug from the sidewalk, but I am not positive that is what started my naturalist journey! I can’t seem to pick one group of organisms I’m interested in: in high school it was mold, college it was fungi, insects, woody plants, and finally freshwater algae and ciliates. In my final semester at University of Michigan I did my independent research on green jelly blobs you could find in many of the freshwater bodies around northern Michigan. In these blobs, colonies of Ophrydium (ciliates), there was an abundance of one species of diatom that had never been discovered before. This research led me to my first publication and showed me how many organisms haven’t been discovered, and how much I could illuminate about the natural world.

I’ve used iNaturalist to embrace my love for all different taxa and connect with other researchers and general nature enthusiasts to learn more about the organisms around me. Almost everything I have learned about southern California marine invertebrates has been from following other iNaturalist users and getting feedback on my posts. The platform has given me an outlet for sharing discoveries that I would have not even known were discoveries if it wasn’t for users on iNaturalist. If I’m out SCUBA diving or near the ocean observing organisms, I’ll always find a way to tell people about iNaturalist and how they can teach themselves about our amazing biodiversity.

During low tides you can find me tide pooling, usually looking for a sea slug species I haven’t found yet, but often I am distracted by crustaceans and snails. On this particular evening, we were graced with the usual sea slugs and snails but it started with a small moray eel biting my boyfriend’s finger! He quickly recovered from the attack and we went back to exploring. I was stunned to see a big funky amphipod grasping the red comb algae on the pools’ edge. It was so relaxed. I had my lights and camera on it for 10 minutes, with smaller energetic amphipods hopping on its back and whizzing around. I didn’t know its name at the time but I knew it was a species I had never seen before, especially in this color variation.

The name of the amphipods is Thorlaksonia platypus, an appropriate name for its big bill-like snoot (proper term for rostrum, anterior end of the head). It is a classic example of Batesian mimicry as its appearance attempts to replicate another animal, a Carinate Dove snail, Alia carinata. Thorlaksonia Platypus...“adopts a stance sitting on an algal surface which strongly resembles the size, outline, and orientation of the columbellid snail Alia carinata. The coloration of the amphipod is also banded to closely resemble that of the mollusk shell” (Crane 1969). Amongst these pools there are plenty of Alia carinata so that makes perfect sense. I ended up finding at least two T. platypus and some other Pleustidae species that haven't been identified yet. All of them were beautiful! People don’t generally pay too much attention to amphipods, but they can look really weird and act in funny ways like we are the audience to their late night talk show skit.

My interest in nature has led me to my position as a first year PhD student at UCSB studying sponge ecology, biodiversity, and endosymbionts. One direction I'm leaning towards is looking at the biodiversity that rely on sponges as habitat in the kelp forest, which would include amphipods. Although I’m a researcher, I see myself as a naturalist interested in all life, especially marine invertebrates, so iNaturalist feels like a home to me where I can nerd out about everything! I hope to bring more attention to community science while at UCSB and find more ways to engage the public with the ocean. A way that I have attempted to engage more with nature is through my art practice. This includes drawings of many underappreciated invertebrates that I am drawn to in the tide pools or while diving.

(Photo of Siena by Zach Berghorst - @amidzooids)

@clauden wrote this to me, regarding Siena's Observation: "when Leslie Harris identified it, [it] became the first confirmed record of the species on iNat. Then she went and commented on my earlier id of this species in Oregon, leading me to correct my error (it's restricted to SoCal) and then review others, having checked references and keys (and included in ID). So in a short period (days), iNat went from some general amphipod records, some flawed, to several certified and high quality observations of a bizarre and colorful crustacean that has...had few observations and no good photos for decades, and now available on GBIF for all...This is the power of the community (members) coupled with the tool (iNat platform) and the data (observations)."

- here's Siena's illustration of Thorlaksonia Platypus!

- cool video showing some of the amazing amphipods of Antarctica!

- check out some of the most faved Amphipods on iNat!

Posted on December 21, 2021 09:56 PM by tiwane