Amphipholis squamata
ECHINODERMATA
Ophiuroidea
โญ๏ธ๐โญ๏ธ Did you know that Brittle Stars are relatives of starfish? Yep, they belong to the same family! That explains why they also have 5 armsโฆ
๐ช๐ ๐ฆพ As you can see, these arms are very delicate, but guess what, they can fully regenerate! That probably explains why this guy have 3 shorter arms, indicating he might have lost them at one pointโฆ
๐ฑ๐ช๐ช And wait, there is even more! Brittle stars can also perform ๐ฎ๐๐๐ผ๐๐ผ๐บ๐, meaning they can voluntarily detach their arms as a defense mechanism. Talk about a handy escape plan!
๐๐ช๐ย Brittle stars are ๐๐๐๐๐๐๐๐๐ ๐, a name derived from the Greek words ๐ฐ๐ฑ๐ฉ๐ช๐ด (“serpent”) and ๐ฐ๐ถ๐ณ๐ฐ๐ด (“tail”) perfectly describing their snakelike, scale-covered arms. I just love watching as they gracefully move away!
๐โญ๏ธThis is the dwarf brittle star or ๐ผ๐ข๐ฅ๐๐๐ฅ๐๐ค๐ก๐๐จ ๐จ๐ฆ๐ช๐๐ข๐๐ฉ๐: one of the smallest ophiure. They belong to Echinoderms, like sea stars and sea urchins, and thus have the typical radial symmetry!
๐ฟ๐ฆทThe central disk has a diameter of 5mm maximum and contains all the internal organs. Another time I will show you the ventral side with its impressive 5 jawsโฆ
๐ช๐ฆพEach of the 5 arms is approximately 4x times longer than the diameter of the disk and attached to it under the radial shields. The arms are supported by an internal skeleton of calcium carbonate plates called vertebral ossicles, forming a spine-like structure. These “vertebrae” are articulated by means ofย ball-and-socket joints, and are controlled by muscles.
โจ๐กLast but not least, these star brittles are bioluminescent, and can produce light as a defense mechanism! With their ability to do autotomy, they can detach one of their glowing arm as a luminous bait to distract their predator and escape! How CRAZY is that!
Sources
- MarLIN
- Doris
- Delroisse Jรฉrรดme, Ullrich-Lรผter Esther, Blaue Stefanie, Ortega-Martinez Olga, Eeckhaut Igor, Flammang Patrick and Mallefet Jรฉrรดme (2017) A puzzling homology: a brittle star using a putative cnidarian-type luciferase for bioluminescence,Open Biol.7160300 http://doi.org/10.1098/rsob.160300
- Deheyn D, Mallefet J, Jangoux M. Expression of bioluminescence in Amphipholis squamata (Ophiuroidea: Echinodermata) in presence of various organisms: a laboratory study.ย Journal of the Marine Biological Association of the United Kingdom. 2000;80(1):179-180. doi:10.1017/S0025315499001733