Evolution of Maternal Provisioning and Development in the Ophiuroidea: Egg Size, Larval Form, and Parental Care.

The Ophiuroidea is the most speciose class of echinoderms and has the greatest diversity of larval forms, but we know less about the evolution of development (evo-devo) in this group than for the other echinoderm classes. As is typical of echinoderms, evo-devo in the Ophiuroidea resulted in the switch from production of small eggs and feeding (planktotrophic) larvae to large eggs and non-feeding (lecithotrophic) larvae. Parental care (ovoviviparity or viviparity/matrotrophy) is the most derived life history.

Evo-Devo in Ophiuroids: The Switch from Planktotrophy to Lecithotrophy in .

AbstractUnderstanding the evolution of development (evo-devo) in the Ophiuroidea and the pathways in the switch from a feeding to a nonfeeding larva is complicated by the variability in the phenotype of the metamorphic larva, being a reduced yolky ophiopluteus in some species (type I development) and a vitellaria larva in others (type II development). We investigated evo-devo in the family Ophionereididae, a group dominated by lecithotrophic development through a vitellaria larva. We reared the planktotrophic larvae of to settlement to determine the metamorphic phenotype.

Juvenile waiting stage crown-of-thorns sea stars are resilient in heatwave conditions that bleach and kill corals.

The juveniles of predatory sea stars can remain in their recruitment-nursery habitat for some time before their ontogenetic shift to the adult habitat and diet. These small juveniles are vulnerable to a range of factors with their sensitivity amplified by climate change-driven ocean warming. We investigate the thermal tolerance of the waiting stage herbivorous juveniles of the keystone coral predator, the crown-of-thorns sea star (COTS, Acanthaster sp.

Evolutionary modification of gastrulation in Parvulastra exigua, an asterinid seastar with holobenthic lecithotrophic development.

Gastrulation is a fundamental morphogenetic process in development. In echinoderms with ancestral-type development through feeding larvae, gastrulation involves radially symmetrical invagination of cells around the blastopore. Gastrulation in the seastar Parvulastra exigua, a species with non-feeding larvae deviates from this pattern.

Unshelled abalone and corrupted urchins: development of marine calcifiers in a changing ocean.

The most fragile skeletons produced by benthic marine calcifiers are those that larvae and juveniles make to support their bodies. Ocean warming, acidification, decreased carbonate saturation and their interactive effects are likely to impair skeletogenesis. Failure to produce skeleton in a changing ocean has negative implications for a diversity of marine species.

Sea urchin fertilization in a warm, acidified and high pCO2 ocean across a range of sperm densities.

Marine invertebrate gametes are being spawned into an ocean simultaneously warming, acidifying and increasing in pCO(2). Decreased pH/increased pCO(2) narcotizes sperm indicating that acidification may impair fertilization, exacerbating problems of sperm limitation, with dire implications for marine life. In contrast, increased temperature may have a stimulatory effect, enhancing fertilization.

Nervous system development in feeding and nonfeeding asteroid larvae and the early juvenile.

Larval and juvenile nervous systems (NS) of three asterinid sea stars with contrasting feeding and nonfeeding modes of development were characterized using the echinoderm-specific synaptotagmin antibody. In the feeding bipinnaria and brachiolaria larvae of Patiriella regularis, the species with ancestral-type development, an extensive NS was associated with the ciliary bands (CBs) and attachment complex. Lecithotrophic planktonic (Meridastra calcar) and benthic (Parvulastra exigua) brachiolariae lacked CBs and the associated NS, but had an extensive NS in the attachment complex.

Temperature, but not pH, compromises sea urchin fertilization and early development under near-future climate change scenarios.

Global warming is causing ocean warming and acidification. The distribution of Heliocidaris erythrogramma coincides with the eastern Australia climate change hot spot, where disproportionate warming makes marine biota particularly vulnerable to climate change. In keeping with near-future climate change scenarios, we determined the interactive effects of warming and acidification on fertilization and development of this echinoid.

Development of the five primary podia from the coeloms of a sea star larva: homology with the echinoid echinoderms and other deuterostomes.

Confocal laser scanning microscopy of larvae of the asteroid Parvulastra exigua was used to investigate the development of the five primary podia from the coeloms in the echinoderm phylum in an approach to the problem of morphological homology in the deuterostome phyla. The development is shown from an early brachiolaria larval stage to a pre-settlement late brachiolaria larval stage. In the early brachiolaria larva, a single enterocoele connected to the archenteron has formed into two lateral coeloms and an anterior coelom.

Evolution of larval form in ophiuroids: insights from the metamorphic phenotype of Ophiothrix (Echinodermata: Ophiuroidea).

Comparison of development through metamorphosis in Ophiothrix species provided insights into the evolutionary relationships between Type I (ophiopluteus only) and Type II (ophiopluteus and vitellaria) patterns of development in the Ophiuroidea. As typical of Type I developers, the six inner larval arms in Ophiothrix spongicola were fully resorbed at metamorphosis and no remnants of ciliated epithelia were retained. The postero-lateral arms function as locomotory organs for the developing juvenile and were discarded at settlement.