Name: late juvenile stage
ECAO ID: 0000560
Definition: "The late juvenile really looks like a small adult. The plates of its endoskeleton have by now densified providing it with a dark shell. In addition, it has finally developed a functional digestive tract. The digestive tract inherited from the larva has indeed by now undergone a complete reorganization, progressively bending within the perivisceral cavity to form two successive loops. The buccal plates and the aristotle lantern have further finished developing, creating a new mouth that has opened on the oral side at the center of the aristotle's lantern, while a new anus has also opened in the periproct, i.e. at the center of the five genital plates. The late juvenile can thus feed and starts growing in size, by grazing on the substrate. The late juvenile is exotrophic, meaning that its growth and development rely on energy derived from external sources. In addition, the primary podia have started to regress by that stage and will eventually disappear, while secondary podia have emerged and are functional, allowing the juvenile to move. Similarly, the immature spines have also started to be lost and be replaced by definitive spines. The genital plate CD has further differentiated into the madreporite and sphaeridia have formed. However, this individual is still sexually immature."
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