Title of Presentation

Dissolved Organic Material Absorption and Distribution by Sea Star Larvae (Asteroidea)

Type of Submission

Pre-recorded Poster

Research Field

Biology

Faculty Advisor

William Jaeckle

Graduation Year

2021

Start Date

10-4-2021 8:00 AM

End Date

11-4-2021 5:00 PM

Abstract

Most sea stars produce free-swimming larvae that feed in order to develop into a juvenile state. Feeding by larvae is typically described as the ability to pick up particulate forms of food. However, in seawater, there is more dissolved organic material (DOM) than particulate organic material. We measured the ability of sea star larvae to take up different forms of DOM from seawater. The larvae were incubated in seawater containing 1.0 mg/mL of iron-containing protein (ferritin) or carbohydrate (iron dextran) for two or six hours. Larvae were preserved at the end of the experiment and the appearance of iron in cells was revealed by the “Prussian Blue” reaction, and each specimen was photographed. The intensity and distribution of the blue reaction product within each larva was measured using the computer program ImageJ. For all larvae incubated with ferritin, the label was most abundant in cells of the stomach-intestine. The label was also detected in cells of the esophagus, coeloms, and the mouth. In the internal body cavities (coeloms), the label seemed to increase with extended incubations, suggesting that absorbed materials are released and distributed into the body cavity. For individuals exposed to iron dextran, the label was also greatest in the cells of the stomach-intestine, but there was no label dispersed within the body cavity. These results suggest that larvae drink seawater and the cells within the digestive system take up DOM from that flow and, after absorption, some of these materials are distributed throughout the larval body.

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Dissolved Organic Material Absorption and Distribution by Sea Star Larvae (Asteroidea)

Most sea stars produce free-swimming larvae that feed in order to develop into a juvenile state. Feeding by larvae is typically described as the ability to pick up particulate forms of food. However, in seawater, there is more dissolved organic material (DOM) than particulate organic material. We measured the ability of sea star larvae to take up different forms of DOM from seawater. The larvae were incubated in seawater containing 1.0 mg/mL of iron-containing protein (ferritin) or carbohydrate (iron dextran) for two or six hours. Larvae were preserved at the end of the experiment and the appearance of iron in cells was revealed by the “Prussian Blue” reaction, and each specimen was photographed. The intensity and distribution of the blue reaction product within each larva was measured using the computer program ImageJ. For all larvae incubated with ferritin, the label was most abundant in cells of the stomach-intestine. The label was also detected in cells of the esophagus, coeloms, and the mouth. In the internal body cavities (coeloms), the label seemed to increase with extended incubations, suggesting that absorbed materials are released and distributed into the body cavity. For individuals exposed to iron dextran, the label was also greatest in the cells of the stomach-intestine, but there was no label dispersed within the body cavity. These results suggest that larvae drink seawater and the cells within the digestive system take up DOM from that flow and, after absorption, some of these materials are distributed throughout the larval body.