Evol Ecol Res 11: 403-412 (2009)     Full PDF if your library subscribes.

Hydra as a model organism to teach biology in secondary schools

Patricia E. Bossert

Stony Brook University, Long Island Group Advancing Science Education (LIGASE), New York; Nassau Community College, Garden City, New York; Eastern Suffolk Board of Cooperative Education Services (BOCES), Holbrook, New York, USA

Correspondence: P.E. Bossert, 13 Woodpath Drive, Northport, NY 11768, USA.
e-mail: pbossert@optonline.net


Aim: Using a personal narrative, highlight the influence that university research can have on secondary education.

Questions: How does the presence of algae in individual hydra affect hydra regeneration? What is the role of hydra body size in the response? How do hydra respond to red and blue light?

Organisms: Two strains of the green hydra, Hydra viridissima, one larger than the other.

Methods: Laboratory experiments with the simplest of materials and apparatuses.

Results: Brown hydra, which have no algae and are larger than green hydra, regenerate more successfully after food deprivation than do green algae. But green hydra in well-lit environments may lose control of their algae and find their intracellular spaces overgrown, leading to failure of regeneration and to disintegration of their cells. This fate was more likely in the larger strain of H. viridissima. Hydra are positively phototaxic to blue light and negatively phototaxic to red light.

Conclusions: There is a trade-off between body size and the ability of hydra to take advantage of an algal endosymbiont. Large hydra species and strains may be harmed by the algae within. Hydra have supported scientific awakenings in faculty and students of secondary schools.

Keywords: gene expression, hydra model, phototaxis, regeneration, teaching secondary school inquiry-based biology.

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