Their minute larvae have a reduced brachiolar complex comprising three small nonsticky protrusions that cannot function in attachment, and some embryos do not develop brachia at all.
hystera exhibited exploratory settlement behavior and attached to the substratum with their brachia and adhesive disc prior to metamorphosis, in a manner typical of planktonic asteroid larvae.
Differential growth of the lateral brachia results in the formation of three arms equal in length.
Hatching occurs 5-6 days after fertilization and, by this time, the brachia are noticeably muscular and extend through breaks in the envelope to attach to the substratum.
In response to a strong current the brachia stretch in the direction of flow, and only concentrated flow from a pipette will dislodge the larvae.
By days 10 or 11, the brachia are reduced to small stumps around the base of the disk [ILLUSTRATION FOR FIGURES 1J, 2K OMITTED].
Before they hatch, the larvae of Patiriella exigua are similar to the brachiolaria of Patiriella species with planktonic development because they have one long central brachium and two short lateral brachia (Table II).
exigua and Leptasterias hexactis, the early brachiolaria have one long and two short lateral brachia, while the late brachiolaria have arms that are equal in length (Chia, 1968).