Research

Functional and evolutionary physiology of gastropod egg masses

(Collaborations with Dr. Amy L. Moran, Clemson University & Dr. Robert D. Podolsky, College of Charleston)

Tiny aeolid nudibranch

Tiny aeolid nudibranch collected near Little Razorback Island in McMurdo Sound.

 Nudibranch egg mass

Nudibranch egg mass from McMurdo Sound.  Each white
dot is an embryo.

 Tiny nudibranch

Another tiny nudibranch from McMurdo Sound.
Small egg mass of a prosobranch (<em>Lacuna</em> sp.) on eelgrass, collected near Friday Harbor, Washington.

Small egg mass of a prosobranch (Lacuna sp.) on eelgrass, collected near Friday Harbor, Washington.

 McMurdo team

From left to right: Erika Schreiber, Art Woods, Amy Moran, Jon Sprague, Bruce Miller.  We’re standing in front of the Barne Glacier on sea ice in McMurdo Sound.

 A male pcynogonid (sea spider)

A male pcynogonid (sea spider) from McMurdo Sound, with three orange egg masses attached to his ovigers.
Egg mass of <em>Rostanga</em>

Egg mass of Rostanga laid
on a piece of plastic, collected near Friday Harbor Labs, Washington.

 Egg mass of <em>Tritonia diomedea</em>

Egg mass of Tritonia diomedea, from an adult collected near Friday Harbor.

 Adult <em>Tritonia antarctica</em>

Adult Tritonia antarctica on a clam shell, collected from McMurdo Sound.

Embryos of aquatic organisms often are contained in masses that limit diffusion. This work focuses on gelatinous egg masses, which have evolved in numerous freshwater and marine lineages. Embryonic O2 consumption can establish steep O2 gradients in egg masses; hypoxia or anoxia has been observed directly, or inferred from developmental asynchrony of embryos, in egg masses of frogs, fish, molluscs, crustaceans, and polychaetes, and may reduce the quality of juveniles, kill embryos directly, or increase mortality by prolonging development and exposure to benthic predators. These effects are important because the survival and performance of early stages strongly influence population dynamics in marine and aquatic systems. Understanding O2 delivery in egg masses is therefore crucial to understanding both life history evolution of marine invertebrates and for testing optimality models of egg mass design. Likewise, because egg masses lack the complex O2-gathering and distribution systems of most adult eukaryotes, these masses provide a system for understanding relationships between environmental O2 availability and organismal design.

Present research directions:

  • Understanding the details of how egg mass traits-size, shape, temperature, algal commensals-influence internal oxygen profiles. This work occurs primarily at the Friday Harbor Labs.
  • Using egg masses to test the temperature-oxygen interaction model that I proposed a few years ago (Woods 1999).
  • Examining egg mass function in Southern Ocean nudibranchs. The fauna of the Southern Ocean is highly endemic and has evolved under stable, cold temperatures (= 5ºC) for at least 15 million years. These conditions have led to the evolution of unusual physiological and biochemical characteristics, many of which may reflect a comparatively high ratio of oxygen availability to oxygen demand. The goal of the these projects is to understand latitudinal variation in egg mass function as it relates to oxygen availability and temperature, especially in the low-temperature, high-oxygen conditions found at high latitudes. Moran and I and our team spent 7 weeks at McMurdo Station in Fall 2006 and will go back again in Fall 2007. This link has more information on our Antarctic research, including lots of photos.