Sexual reproduction in four Caribbean commercial sponges. III. Larval behaviour, settlement and metamorphosis

Abstract

Larval behaviour, settlement, and metamorphosis were investigated in four Caribbean commercial sponges, Hippospongia lachne, Spongia barbara, S. cheiris and S. graminea, using light and transmission electron microscopy. The parenchymella larvae of these viviparous and gonochoristic species have an average size of 350pm by 420pm when released. Symbiotic bacteria occur intercellularly in both larvae and post-larvae. Laboratory behavioural studies demonstrate that free-swimming larvae display directional swimming with constant lateral rotation and negative phototaxis. Larval settlement occurs 2 6 5 6 hours after release from the parent and involves the formation of a basal lamella between the post-larva and substrate. There is no evidence of larval substrate selection by type or orientation. The canal system begins to form six days after settlement and oscules are apparent eleven days post-settlement. Available evidence suggests that larval ciliated epithelial cells are terminally differentiated and do not appear to contribute to formation of post larva or adult in this group of Porifera.

Vertical transmission and successive location of symbiotic bacteria during embryo development and larva formation in Corticium candelabrum (Porifera: Demospongiae)

“…This clear separation between bacteria and sponge cells seems to be a particular feature of C. candelabrum (and maybe of Homosclerophorida in general) since it has not been reported for any other bacteriosponge examined to date (e.g. Kaye & Reiswig, 1991;Ereskovsky & Tokina, 2004).…”

“…In contrast, bacterial transmission seems to take place during cleavage in most larviparous sponges that produce solid larvae (parenchymella) (e.g. Kaye & Reiswig, 1991). In oviparous sponges, oocytes surrounded by a pseudo-chorion are released to the environment before cleavage takes place (Mariani et al, 2001) and, thus, only during oocyte formation can microsymbionts be acquired from the sponge parental tissue.…”

Transdifferentiation in developmental biology, disease, and in therapy

“…However, it is important to stick to the strict definitions outlined above to identify which of these celltype conversions embody a true transdifferentiation event. For example, during mammalian development, epithelial cell-type switches from stratified squamous to columnar during esophagus development and from pseudostratified to squamous during the development of the female reproductive system have been long identified (Cunha, 1976;Yu et al, 2005 Kaye and Reiswig, 1991). Amano and Hori (1996), used electron microscopy techniques to visualize natural markers of flagellated cells.…”

Depth regulation in parenchymella larvae of a demosponge:relative roles of skeletogenesis, biochemical changes and behavior

“…Symbiotic bacteria are likely to be present in early settlers, as there is usually a direct a transfer from adults to juveniles through the larva (e.g. Levi & Levi 1976, Kaye & Reiswig 1991, Woollacott 1993.…”