Copepod Life Cycle- Beginning and End

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The docks near my house are a lovely place to explore marine life of all sizes. Sea lion and Brandt’s cormorants were hanging out on the wharf as I towed a plankton net off the boat dock. I was curious to see what microscopic life I could find floating in the water right off the boat launch.

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It came as no surprise that I found a copepod swimming around in the collecting jar. Due to it’s shorted antennae and proximity to shore, I think it may have been a Harpacticoid spp. (Quick, copepod experts, let me know in the comment section!) It was so interesting to watch her swim around. She seemed to move in jumping spurts. This is because to such a small organism, the water is actually very viscous. Although water flows smoothly around something as large as a human, smaller animals move as though they are in a large ball pit.

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Copepods have four main life stages: egg, nauplius, copepodite, and adult. The nauplier and copepodite morphs have multiple stages in them as well. Over the course of a copepod’s life, they go through so many transformations, each able to interact with the marine environment in different ways. Their feeding rate actually changes per pound with each life stage. It is not until a copepod reaches adulthood that they have a gender.

Looking at this copepod in particular, I was able to see egg sacks on her posterior end. In this one slide, I was able to see both the end point and the very beginning of a copepod’s life cycle.

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If this copepod is actually Harpacticoid spp., then it lives in both the ocean environment as well as in the sediment near the coast. Copepods are an important food source to many marine animals, including whales.