Ophiura sarsii
- Dataset
- Lateral arm plate morphology in brittle stars (Echinodermata: Ophiuroidea): new perspectives for ophiuroid micropalaeontology and classification
- Rank
- SPECIES
Classification
- kingdom
- Animalia
- phylum
- Echinodermata
- class
- Ophiuroidea
- order
- Ophiurida
- family
- Ophiuridae
- genus
- Ophiura
- species
- Ophiura sarsii
discussion
Remarks: A simplified view of ontogenetic changes in LAP morphology might suggest similar patterns as those related to the position within the adult arm, considering that juvenile LAPs are less differentiated than adult ones. This, however, is only partly the case. In fact, while the spurs on the outer proximal edge in both Ophiacantha fraterna and Ophiura sarsii are lacking in the smaller specimens, the conspicuous vertical striation in O. fraterna is constantly developed in all examined growth stages. Similarly, the ridges and knobs on the inner side and the position, arrangement, relative size and shape of spine articulations show very little ontogenetic variation within the studied size range. Surprisingly, the diffuse oblique area of dense stereom on the ventral portion of the outer surface is a character developed in the juvenile LAPs of Ophiacantha fraterna which gradually fades with specimen size and completely lacks in the largest examined specimen. Whereas in Ophiura sarsii, juvenile proximal LAPs share a certain resemblance with median to distal adult LAPs, the example of Ophiacantha fraterna clearly shows that this is not necessarily always the case. In contrast, juvenile proximal LAPs rather resemble downscaled and ventro-dorsally compacted versions of their adult proximal equivalents.
Name
- Homonyms
- Ophiura sarsii