Most benthic invertebrates have complex life cycles with planktonic larvae that return to the substratum to settle and metamorphose into a benthic stage. Although naturally produced chemical cues have long been thought to be important for the settlement or metamorphosis of invertebrate larvae, few ecologically relevant chemical cues have been clearly identified. The marine echinoid Holopneustes purpurascens has a complex life cycle, with a planktonic, nonfeeding dispersive larva that metamorphoses into a benthic stage that lives in the canopy of subtidal benthic algae such as the red alga Delisea pulchra and the kelp Ecklonia radiata. Recently recruited juveniles are found primarily on D. pulchra, and we hypothesized that this was in response to a chemical cue produced by this alga. Competent larvae metamorphosed in the presence of D. pulchra, or seawater surrounding this alga, but not in response to the presence of E. radiata or its extracts. A cue for metamorphosis was isolated and characterized from D. pulchra and found to be a water-soluble complex of the sugar floridoside and isethionic acid in a 1:1 molar ratio. The floridoside-isethionic acid complex also triggered settlement in H. purpurascens; however, this response was less specific than metamorphosis and was reversible. Larvae of H. purpurascens also metamorphosed in the presence of several other species of red, but not brown or green, algae from their habitat. Floridoside is found only in red algae, suggesting that the floridoside-isethionic acid complex may be acting as a cue for metamorphosis in other red algae as well as in D. pulchra.
Induction of metamorphosis in the sea urchin Holopneustes purpurascens by a metabolite complex from the algal host Delisea pulchra.
J. Williamson,R. de Nys,N. Kumar,D. Carson,P. Steinberg
Published 2000 in The Biological Bulletin
ABSTRACT
PUBLICATION RECORD
- Publication year
2000
- Venue
The Biological Bulletin
- Publication date
2000-06-01
- Fields of study
Biology, Medicine, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar, PubMed
CITATION MAP
EXTRACTION MAP
CLAIMS
CONCEPTS
- delisea pulchra
A red algal host species associated with recently recruited juveniles and used as the source of the inductive cue.
Aliases: D. pulchra
- ecklonia radiata
A kelp species from the same habitat that was tested as a non-inducing algal reference.
Aliases: E. radiata
- floridoside
A sugar compound detected in red algae and identified as one component of the inductive complex.
- floridoside-isethionic acid complex
A 1:1 water-soluble compound complex isolated from Delisea pulchra and tested as a larval cue.
Aliases: floridoside and isethionic acid complex
- holopneustes purpurascens
A marine sea urchin species whose planktonic larvae were tested for settlement and metamorphosis responses.
Aliases: sea urchin Holopneustes purpurascens
- isethionic acid
A water-soluble organic acid identified as the second component of the inductive complex.
- metamorphosis
The developmental transition from a competent planktonic larva to the benthic juvenile stage.
- red algae
A group of algae represented in the habitat by species associated with larval metamorphosis responses.
Aliases: rhodophytes
- settlement
The larval response involving attachment or selection of a substratum before metamorphosis.
REFERENCES
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