Embryonic, Larval, and Early Juvenile Development of the Tropical Sea Urchin,Salmacis sphaeroides(Echinodermata: Echinoidea)

Abstract

Salmacis sphaeroides (Linnaeus, 1758) is one of the regular echinoids, occuring in the warm Indo-West Pacific, including Johor Straits, between Malaysia and Singapore. In order to investigate the developmental basis of morphological changes in embryos and larvae, we documented the ontogeny of S. sphaeroides in laboratory condition. Gametes were obtained from adult individuals by 0.5 M KCl injection into the coelomic cavity. Fertilization rate at limited sperm concentration (10−5 dilution) was 96.6 ± 1.4% and the resulting embryos were reared at 24°C. First cleavage (2-cell), 4-cell, 8-cell, 16-cell, 32-cell, and multicell (Morulla) stages were achieved 01.12, 02.03, 02.28, 02.51, 03.12, and 03.32 h postfertilization. Ciliated blastulae with a mean length of 174.72 ± 4.43 μm hatched 08.45 h after sperm entry. The gastrulae formed 16.15 h postfertilization and the archenteron elongated constantly while ectodermal red-pigmented cells migrated synchronously to the apical plate. Pluteus larva started to feed unicellular algae in 2 d, grew continuously, and finally attained metamorphic competence in 35 d after fertilization. Metamorphosis took approximately 1 h 30 min from attachment to the complete resorption of larval tissues and the development of complete juvenile structure with adult spines, extended tubefeet and well-developed pedicellaria, the whole event of which usually took place within 1 d postsettlement. This study represents the first successful investigation on embryonic, larval, and early juvenile development of S. sphaeroides. The findings would greatly be helpful towards the understanding of ontogeny and life-history strategies, which will facilitate us to develop the breeding, seed production, and culture techniques of sea urchins in captive condition.

Sea Urchins (Echinodermata: Echinoidea): Their Biology, Culture and Bioactive compounds

“…Some may have white spines with maroon bands, others with all maroon spines, and yet others with green and maroon bands. It can be found in the warm temperate regions including Johor Straits, between Malaysia and Singapore [14,15,44]. This sea urchin can be occurred at depth range between 0 and 90 m, however it is also found in shallow waters, especially in amongst sea grass meadows, coral reef and in muddy sublitoral zone or washed ashore [43].…”

“…Gametes from both female and male urchins are obtained by injecting 0.5 M KCl into the coelomic cavity. Eggs are collected by inverting female urchins over a glass beaker filled with filtered sea water (FSW), while sperms in the most concentrated form are pipetted off the genital pores [14,45,51,52]. Fertilization is usually done at limited sperm concentration and the resulting embryos are reared.…”

Guide to Appropriate Literature Survey and Scientific Writing

“…It should include description of the techniques used so someone could figure out what experiments were actually done. The details of a published protocol do not need to be reproduced in the text but an appropriate reference should be cited -e.g., simply indicate "were done as described by Rahman et al [11]". Any changes from the published protocol should be described.…”

Influence of temperature variation on embryonic and early larval development of a commercially important tropical sea urchin Tripneustes gratilla (Linnaeus, 1758)

“…Captive Sabah breeding was attempted by adding 2 ml of 0.5M of KCl into the coelomic cavity of both male and female sea urchins (Rahman et al, 2000;2005;2012b). Later on, the eggs were collected by inverting the female to a glass beaker filled with 2 µm filtered seawater (FSW).…”