Oysters (see Figure 1) are bivalve molluscs, meaning their shells consist of two hinged parts, which protect their soft bodies (mollis = soft). They live in marine or brackish (slightly salty) habitats. When feeding, these invertebrates draw water over their gills and filter out small particles and plankton via tiny hairlike projections called cilia. This filtering process can concentrate harmful bacteria present in the water around them. This means that eating uncooked oysters can pose the threat of transmitting diseases such as cholera. Cholera is an infectious disease transmitted by Vibrio cholerae (see Figure 2). This bacterium causes vomiting and diarrhoea. In developing countries, contracting cholera can lead to death owing to extreme dehydration. As a result of bad weather and flooding in the UK recently, a number of oyster farms have had to close due to contamination of the animals with harmful strains of E. coli.
Bats are the only living mammals that can fly. Vampire bats (see Figure 4) live up to their name by feeding on blood. Once these nimble creatures detect their bird or mammal prey by echolocation, specialised heat sensors in their noses lead them to the blood-filled regions of the animal victims. Unlike fictional ‘blood-sucking’ vampires, the bats then make a small incision in the prey animal with their razor-sharp teeth and lap the blood from the wound with their tongues (see http://tinyurl.com/ntojwro). Their saliva contains anticoagulants that prevent the blood from clotting, so the bats can feed from a wound for 20–30 minutes typically.
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