Vinacrawler

The vinacrawler diverges from the vinagobble by taking on a mobile lifestyle, crawling across the ocean floor, instead of burrowing upon adulthood. The biggest resulting change is in the limbs. The upper limbs no longer develop into grabbing tentacles; instead, all eight limbs develop much like the ancestral lower limbs did. Those originally served to hook the vinagobble in place, but now these stubby limbs act as legs, split in two at the end. Where the vinagobble had tough claw-like projections, these are now reinforced by strontium to form claws.

The limbs' configuration is the other biggest change in their development. When laid upon the ocean surface, only half of a vinagobble's limbs would have pointed downward. In the vinacrawler, they have moved so that they now all face downward, in four pairs of legs. This has given them the beginning of cephalization, as the front around the mouth acts as a head, with clusters of nerve cells to coordinate their senses and movements. They are nearly blind but have a limited ability to sense light using a line of black eyespots above the mouth. They are also sensitive to vibrations and scents. A line of yellowish chemical sensors runs below the rim of the mouth.

Aside from these significant shifts in external morphology, the vinacrawler's internal systems work much as before. A large ribbed stomach with a gaping mouth constitutes most of the body volume, full of ribbon-tailed detriti microbes to help digestion and containing many tiny digestive hairs. They now subsist only on filter-feeding due to the loss of the grabbing tentacles. The membrane over the mouth has been lost as it is no longer useful.

They maintain a system of vents and pockets of fluids throughout the body, allowing a constant flow of water into the mouth, then expelled outward. These include a row of outward-facing vents on each side and a line of vents above the mouth, along with many inward-facing vents throughout the stomach. The fluid pockets also provide a hydrostatic mechanism for the legs to move. This pressurized fluid keeps the legs firm.

Much as before, the vinacrawler has four reproductive organs, at the base of each of the four hindmost legs. These constantly produce sperm, which they eject, and eggs, which they retain in their body. These eggs develop within a sac into larvae, whether fertilized or not; once old enough, they expel the larvae into the open ocean. They pass through an embryonic state as simple globe-shaped clumps of cells, but by the time the larvae are expelled, they have developed a form similar to a smaller version of an adult vinagob, free-swimming and bioluminescent. Eventually, their fins migrate around the body and become legs, they lose lights, and they sink to the ocean floor.