Tuesday, July 19, 2011

Another Potential Threat to Native Species?

Recently, I was reading an aquatic nuisance species newsletter. In it, there was a little snippet about a creature called a ‘tadpole shrimp’, Triops longicaudatus. This animal is apparently sold as a novelty pet, sort of like sea monkeys. They are crustaceans with 3 little eyes and can grow to 2 ½ inches in length. They are sometimes called the dinosaur shrimp, having changed little in the last 200 million years.

Triops are interesting creatures, indeed, and is a very successful animal. They have become adapted to living in vernal pools or temporary ponds. In the winter and spring, as these ponds fill with water, the Triops eggs hatch. Within a few weeks, they can reach 2 inches in length. Being omnivores, they eat almost anything from algae to shrimp and insects, sometimes even their own siblings. After maturing they lay eggs. Triops can live up to 90 days, but die once the water dries up in the pool. The eggs remain in the dirt of the dried up pond, until the next rain.

Triops eggs are extremely hardy. The eggs can withstand freezing temperatures as well as hot temperatures over 200 degrees F for over half a day. They can also remain in a dormant stage for up to 20 years. Because they are adapted to living in temporary pools, the eggs must completely dry out before they can hatch, therefore these animals cannot live in permanent water bodies.

Tadpole shrimp are gaining enormous popularity as pets with many websites dedicated solely to the care and raising of these animals. They are cute and novel but we all know what sometimes happens when people get tired of or outgrow their aquarium inhabitants. Do you remember all those rusty crayfish which were used for educational instruction? Once the studies were over, the instructors or students would release them into the nearest water body, not realizing the impact the non-native crayfish might have on the ecosystem. The result: the rusty crayfish not only displaces our one species of native crayfish but also dines on fish eggs. Will Triops become such a threat to animals native to our vernal pools?

What do you think of shipping these animals all over the world? What might their potential impact be on native species if they are released?

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