Glossary

acoustic tagging: tags that can be attached to animals. They emit sound signals that can be picked up by receivers and allow animals to be detected and tracked.

adaptation: how an animal changes features over generations to better survive in its environment

ampullae of Lorenzini: sensors in a shark’s snout that allow it to pick up electrical signals created by motion in the water

apex predator: the top feeder in a food chain

autonomous underwater vehicle (AUV): a diving robot operated remotely or by preprogramming without an onboard pilot or a tether linking it to a ship

barnacles: crustaceans that anchor onto rocks, shells, boats, or other hard undersea surfaces and that filter seawater to get their food

benthic: seafloor or deep dwelling

biofluorescence: a type of glowing effect created by fluorescent molecules, which absorb and reemit light

bioluminescence: another type of glowing effect created by light-emitting molecules in which an enzyme (luciferase) stimulates a compound called luciferin

bycatch: the accidental catch of a fish while fishing for other species

caudal: referring to the tail of a marine animal

chemoreception: in sharks, a highly refined sense of smell and taste combined

Chondrichthyes: the class of animals to which all the species of sharks belong

citizen science: interested laypeople (not professionals) contributing data they collect from their surroundings and expeditions to scientific researchers

claspers: elongated fins that allow male sharks to hold onto females during mating

Crittercam: a camera that can be attached to an animal to record its behavior and experiences in the wild

denticle: a tooth-shaped scale embedded in sharkskin. The scales make sharks hydrodynamic, assisting them in swimming fast.

distribution: the number of animals over a range of land or sea

diversity: the number of different species of animals over a range of land or sea

dorsal: on the back

ecosystem: a community of living organisms (plants and animals) and nonliving components such as air, water, and soil that interact to create a functioning, interconnected system

electromagnetism: a force created by the interaction between the electrically charged particles in all molecules

electroreception: the ability to detect electrical charges, such as those created by live animals

endotherm: the ability of a marine animal to heat its own body to a temperature that is warmer than surrounding water

food chain: a hierarchical system of organisms that rely on one another for nutrition. For example, sharks eat smaller fish that eat smaller krill that eat smaller plankton.

gestation period: the length of time it takes a pregnancy to reach full term (ready for birth)

gills: slits on the head and neck of a shark through which water passes, allowing the shark to process the water for oxygen; the breathing organs of a shark

GoPro: the brand name of a small video camera that can be mounted onto solid surfaces to capture live action, including underwater

habitat: the area an organism relies on for nutrition, shelter, mating, and other needs

ichthyologist: a scientist who studies sharks and other fish

ichthyology: the scientific study of sharks and other fish

lateral line: a row of pressure sensors along a shark’s side

mechanoreception: the ability to detect motion. Shark mechanoreception comes through their lateral lines, ampullae of Lorenzini, and nasal barbels.

nasal barbels: sensors that dangle from a shark’s head to allow it to sense prey on or below the seafloor

niche: a position in the food chain and environment to which an animal adapts to thrive there

nictitating membrane: an extra eyelid or fold of skin that covers a shark’s eye when it attacks another animal. The fold protects the eye from damage.

Osteichthyes: the class of animals to which all the species of bony fish belong

pelagic: open ocean

photoreception: a sense of vision and light. In sharks the photoreceptors are extra sensitive to blue light, which allows them to see in deeper, darker waters than humans can.

placoderms: a group of bony fish from which scientists believe sharks evolved

population: the number of a group of animals of the same species

spiracles: small head organs that assist some species of shark with breathing

stocks: the natural number in a population of animals prior to overfishing or other depletions

telemetric buoy: an apparatus that sits in or on the surface of water to gather and transmit data. For example, a transmitter tag on a shark sends signals about the shark’s location to the buoy, which sends the data by satellite back to a land-based computer where a scientist reads it.

tonic immobility: a state induced by turning a shark upside down, rendering it briefly paralyzed. This state can be useful to some animals that avoid predators by appearing to be dead.

ventral: on the front