isopod marsupia aren’t really “pouches” but more of a transparent membrane grown on the belly that fills with nutrient-rich liquid and embryos.
the first isopod hasn’t grown a new marsupium after giving birth, so the belly is just segmented and smooth. the second has developed eggs, visible as greenish-yellow spheres inside the membrane. the final isopod is due to give birth in a day or two, with the juveniles already having developed legs, eyes, and everything within the marsupium.
you can actually see the segments, tails, and legs of the babies through the marsupium!
because marsupia aren’t very thick, a stressed female isopod (such as one grabbed by a predator) close to giving birth will break the membrane and expel the young immediately, giving them a chance at escaping.
