Concept explainers
Sustainable Use of Horseshoe Crabs Horseshoe crab blood clots immediately upon exposure to bacterial toxins, so it can be used to test injectable drugs for the presence of dangerous bacteria. To keep horseshoe crab populations stable, blood is extracted from captured animals, which are then returned to the wild. Concerns about the survival of animals after bleeding led researchers to do an experiment. They compared survival of animals captured and maintained in a tank with that of animals captured, bled, and kept in a similar tank. FIGURE 24.28 shows the results.
FIGURE 24.28 Mortality of young male horseshoe crabs kept in tanks during the 2 weeks after their capture. Half the animals were bled on the day of their capture. Control animals were handled, but not bled. This procedure was repeated 8 times with different sets of horseshoe crabs.
In which trial did the most control crabs die? In which did the most bled crabs die?
To explain: The trial in which the most control crabs died.
Introduction: Horseshoe crabs belong to the Phylum Arthropod. They are normally found around shallow ocean waters. Horseshoe crabs are living fossils. The horseshoe crabs though they look like crustaceans are marine arachnids.
Explanation of Solution
The uniqueness of horseshoe crabs is that they clot upon encountering bacteria. Therefore, they are used in experiments where highly virulent bacteria are involved. The blood of horseshoe crabs is taken and then let out in their habitat in order to conserve their population, but this might also lead to their death. Therefore, experiments were conducted to check their survival after taking their blood.
In trial 5, the number of control crabs is 30, and 1 crab died out of it.
The trial group 5 marked the highest number of control crabs that died.
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Chapter 24 Solutions
Biology: The Unity and Diversity of Life (Looseleaf)
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