Amphipholis squamata

U
ECHINODERMATA
Ophiuroidea

โญ๏ธ๐ŸŒŸโญ๏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 armsโ€ฆ

๐Ÿ’ช๐Ÿ”„ ๐Ÿฆพ 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 pointโ€ฆ

๐Ÿ˜ฑ๐Ÿ”ช๐Ÿ’ช And wait, there is even more! Brittle stars can also perform ๐—ฎ๐˜‚๐˜๐—ผ๐˜๐—ผ๐—บ๐˜†, meaning they can voluntarily detach their arms as a defense mechanism. Talk about a handy escape plan!

๐Ÿ๐Ÿ’ช๐Ÿย  Brittle stars are ๐’๐’‘๐’‰๐’Š๐’–๐’“๐’๐’Š๐’…๐’”, a name derived from the Greek words ๐˜ฐ๐˜ฑ๐˜ฉ๐˜ช๐˜ด (“serpent”) and ๐˜ฐ๐˜ถ๐˜ณ๐˜ฐ๐˜ด (“tail”) perfectly describing their snakelike, scale-covered arms. I just love watching as they gracefully move away!

๐ŸŒŸโญ๏ธThis is the dwarf brittle star or ๐˜ผ๐™ข๐™ฅ๐™๐™ž๐™ฅ๐™๐™ค๐™ก๐™ž๐™จ ๐™จ๐™ฆ๐™ช๐™–๐™ข๐™–๐™ฉ๐™–: one of the smallest ophiure. They belong to Echinoderms, like sea stars and sea urchins, and thus have the typical radial symmetry!

๐Ÿ’ฟ๐ŸฆทThe 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 jawsโ€ฆ

๐Ÿ’ช๐ŸฆพEach 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.

โœจ๐Ÿ’กLast 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
Copyright © 2024