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Marine Biology Research

Many tropical coral reef marine fishes change sex during their lifespan depending on the social conditions.  For example, clownfishes typically live most of their life on or in very close proximity to a sea anemone in small groups from 3 up to 6 or 7 depending on the size of the anemone.  In these groups, the largest is usually the reproductive female, the second largest, the male and the smaller individuals are undifferentiated.  If the female is removed, the male will transform into a female in a matter of weeks.  Immediately, within the first few minutes, the male will begin to display female-typical behavior, e.g., court the other smaller fish.  Within a few weeks, the testes of the male will have been absorbed, and ovaries will replace them.  In addition, the size of the fish will increase, and the genitalia will change shape to allow for the passage of eggs instead of sperm through the genital duct.  At the same time, the largest of the undifferentiated fish will transform into a male following a similar time course.  This is one of the most remarkable and dramatic examples of plasticity in nature, the complete morphological sex transformation dependent completely on sensory input that dictates differences in the social environment.  Despite a large literature describing the ecology and natural history of this incredible phenomenon, very little is known about how the brain orchestrates the transformation.  Presumably, the brain is the organ that initially receives the sensory information from the change in the social environment, and then via unknown changes in neural control, changes the central commands that orchestrate the hormonal signals that ultimately change morphology and sex.  The purpose of this research program is to make progress understanding the neurobiology that underlies the sequential hermaphroditism of the clownfish.  Currently we are applying similar techniques that we have been using in the mouse to study plasticity and function of the nervous system in the fish, e.g., measuring adult neurogenesis, neural activity using immunohistochemical detection of immediate early genes, and morphology and anatomy using nissl stains, microscopy and image analysis.

For more pictures of our experimental setup, please visit our photo gallery.

Fish in Our Display Tank

Red Lionfish (Pterois volitans)

Native to the coral reefs of the Indo-Pacific and the Red Sea. Lionfish are members of the family Scorpaenidae, the Scorpionfish, that contains some of the most venomous animals in the world.  The spines of the Lionfish contain a venom that is usually not lethal to humans but causes pain and temporary paralysis. When threatened, the fish often faces its attacker in an upside down posture and extends its spines for defense.  Lionfish are ambush predators, preying on fish and shrimp that venture too close to their large mouth.

Yellow Tang (Zebrasoma flavescens)

Native to the coral reefs of the Indo-Pacific. The Yellow Tang is a member of the family Acanthuridae, the Surgeonfish.  The white mark on the caudal peduncle, near the tail, is a sharp barb that can be flashed to the side for defense. Tangs are omnivorous, eating both plant and small animal material.

Blue Tang (Paracanthurus hepatus)

Native to coral reefs of the Indo-Pacific. The Blue Tang, similar to the Yellow Tang, is a member of the family Acanthuridae, the Surgeonfish.  It also has a sharp barb that can be flashed to the side for defense.

Queen Coris (Coris frerei)

Native to the coral reefs of the Indo-Pacific. The Queen Coris or Formosa Wrasse is a member of the family Labridae, the Wrasses.  Wrasses, like many other related coral reef fishes, change sex during the course of their lifetime starting off as females and then changing into males when they become large enough to defend a territory.  The Queen Coris eats small fish, shrimp, worms and snails.

Red-Knobbed Starfish (Protoreaster linckii)

The Red-Knobbed starfish is native to coral reefs of the Indo-Pacific.  Starfish are echinoderms, a group of marine invertebrates that includes sea urchins and sea cucumbers.  Red-Knobbed starfish eat snails, clams, dead fish, shrimp, worms or other animal and plant material on the ocean floor.  When feeding their stomach can exit the underside of their body surround the food and then retract into the body.

For more pictures of fish from our display tank, please visit our photo gallery.