A) This is the gill tank. It contains water and gills. The creature pulls air in its mouth and forces bubbles through the water to keep it oxygenated.
B) These are the exit nostrils that allow the air to escape from the gill tank.
C) This is the mouth. It sits at the end of a muscular tube. This creature is only capable of sucking up liquids.
D) This is the hox tail. The embryology of myriapod chordates is such that stem cells continue to create new segments from the end until hormones signal them to stop. The retention of the hox tail allows there to be closely related species with very different numbers of legs, as well as species that continue to add legs for life.
E) These are eyes. This creature is able to see in all directions. The skin of these animals is both bioluminescent (under the right circumstances) and light-sensitive, but only where the lenses grow is it able to form images.
F) The anus is located here. As the hox tail adds more segments, it is able to migrate further posterior. These creatures tend to bury their fecal matter with their hind legs.
G) Protective flaps have formed to cover the exit nostrils, keeping out dust while it burrows.
H) The forward two legs have fused together into a single trunk underneath the mouth. The immature nymphs are born without this appendage and are dependent on liquids regurgitated by the parents. Since the limbs are capable of regenerating, so is the trunk. Members of the band whose trunks are ripped off by wily prey are nursed as children until their trunks regenerate.
I) The digits of the limb have become more muscular and capable of mashing food between them. They act as jaws and the muscular tube of the mouth acts as a tongue.
J) The next set of digits is used for grasping and carrying.
K) The hindmost set of limbs have also fused together, forming a tube between them, sealing off the true anus and forcing feces down the tube and out the end. The new limb is used to bury feces underground so they will not continually step in them while they move throughout the burrows.
L) Being redundant by having the same field of vision as the second set of eyes, the first set of eyes is reduced.
M) The second set of eyes becomes larger and more sensitive.
N) The third and fourth sets of eyes replace their retinas with powerful light-producing patches, using the remaining lenses to shine directed beams around the animal, enabling it to see underground.
O) The fifth set of eyes moves backwards slightly, but otherwise remains the same, allowing the animal to see behind.
P) This entire clade of animals lacks sperm cells and egg cells as mammals would understand them. Instead, male epithelial cells are capable of fusing with any female epithelial cells, but the zygotes only survive where they can implant a placenta undisturbed, such as in an armpit or under the hox tail. Females are picky about whose cells they allow into those areas and will clean out unwanted zygotes. In the creature above, the space between the secondary digits of the trunk has become a pouch for incubating embryos in the females and a zone of loose cells in males.
Q) Only females have this tentacle and use it to wipe up male cells and place them into their incubation pouches. Females are the ones that initiate mating and will use their tentacles for displays.
R) The trunk is now completely fused around the oral tube inside.
S) The first set of eyes has now totally disappeared.
T) The fourth set of eyes have flattened into luminescent patches covered by a lensing material. Using both muscles and fluid flow, the creature is able to wrinkle the material in such a way to form symbols to signal others. This is their primary means of communication.
U) The nostril flaps have developed thin membranes capable of detecting loud sounds, becoming ears. Their sense of hearing is still very limited and can only be used in between bursts of escaping bubbles.
V) Feeding on new forms of plant life, these creatures have adapted to being perpetually bloated.
W) The fifth set of eyes has moved even further back to the point that bending the tail (formerly the fifth pair of legs) allows the animal to see forward with them. This is important, since their forward-facing eyes are so sensitive that the beams from the former third set of eyes of other animals can temporarily blind them.