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Short-armed ambraki (Platybrachius fabiensis) [flat armed bean dweller]

Creator: Kopout
Ancestor: Reef Ambraki
Habitat: Nergali-Beans Hotspot
Size: Juvenile: 5mm wide, Adult: 1.6 cm tall
Support: Soft-Bodied (Hydrostatic Skeleton)
Diet: Filter-feeder (Juvenile, <200μm; Adult, 500μm-700μm), photosynthesis
Respiration: Passive (diffusion)
Thermoregulation: Ectothermic
Reproduction: Asexual (fragmentation), Sexual (Isogamous broadcast spawning, Epitoke tentacles)

The short-armed ambraki split from its ancestor and has grown much taller. Much of this height come from the long pedal and apical arms at the top and bottom of the organism but they also have a stretched central core, from which the arms emerge. This stretching has had the side effect of vertically elongating the bases of the side arms. These lateral arms do not extend out as far from the core region, giving them the appearance of four large mouths attached to the side of the cylindrical body.

The stretching of the central region has had another beneficial effect, the duplication of their ancestor’s reproductive protrusions. While their ancestors only had single protrusion between each of their lateral arms the short-armed ambraki has four at each junction, for a total of sixteen. These protrusions are hollow, and the inner cavity is lined with reproductive cells. These reproductive cells are haploid and produce gametes by mitosis. Gametes are then shed into the water and drift in the current until they come inContact with another gamete and fuse. In addition to this if two short-armed ambrakis are close enough one may insert a feeding tentacle into the reproductive tube of its neighbor. In this case the cells on the surface of the tentacle are stimulated to undergo miosis, producing haploid cells which fuse with the gametes of the other ambraki. Afterwards the tentacle is shed from its parent and swims away using its cilia. The zygotes grow attached to the tentacle and with its support they become more developed than those produced by spawning. A free-swimming tentacle has limited ability to feed as it lacks a specialized digestive cavity and will eventually starve, but not before budding off many offspring. They also remain capable of reproduction by fragmentation, though this is mostly done by juveniles.

Juveniles have changed little from their ancestral form. The have six arms, arranged equidistantly around a core which is also home to eight photo receptor patches. Like in the adult the arms have gastric cavities, with eight tentacles emerging from each of them. When juveniles reach approximately five millimeters in diameter, arm tip to arm tip, they settle onto the substrate and begin metamorphosizing into adults. The arm attached to the substrate becomes the pedal arm while the arm directly above it becomes the apical arm. The other four arms do not grow as quickly or as long as these two, instead becoming the short, wide side mouths of the adult. They most often recruit to sandy substrates where the tentacles of the pedal arm burrow can burrow in and providing better support. They will occasionally feed on substrate dwelling microbes with their pedal tentacles. They are able to cling to hard surfaces as well. When doing so they produce large amounts of mucus from their pedal tentacles which helps secure their hold. While adults are largely sessile, they are capable of limited movement using their pedal tentacles. This is very slow, and mostly used if their location becomes unsuitable for some reason. More rarely it may be used in preparation for mating with another ambraki which is close by but out of tentacle range.

Like their ancestor they have six gastric cavities, one on each of their arms. Eight ciliated tentacles emerge from inside each of these. The tentacles are mobile and ciliated. The tentacles move in a spiraling motion creating a feeding vortex which draws in small food particles. The tentacles are coated in a sticky mucus, when food, whether plankton or nonliving particles, comes into contact with them it is trapped in his mucus and transported into a ciliated groove which pulls it down to the gastric cavity at the base of the tentacle.

They lack a circulatory system, instead having an intercellular medium similar to a sponge’s mesohyl which facilitates diffusion of nutrients throughout the organism and acts as a hydrostatic support.

This post has been edited by kopout: Mar 6 2023, 05:38 PM

A quick check: if you're adding the ground to the image, it makes sense to also provide the rest of the background. A solid blue color for the surrounding water will do.

fixed