Porpoises, like all toothed whales (odontocetes) use sound for echolocation and communication. Echolocation allows porpoises to “see” with sound. It helps them to navigate their surroundings, locate objects and prey. Porpoises also use high-frequency whistles for communication.
How does ocean pollution affect porpoises?
Many contaminants are lipophilic, meaning that they dissolve in fats (lipids). Porpoises have blubber, a thick layer of fat underneath the skin that keeps them warm. And that is where contaminants accumulate over time and get stored. Porpoises have a very high metabolic rate, meaning that they need to eat constantly. They can be described…
What are mental maps?
Porpoises maintain mental maps, a mental image of their surroundings, which also includes the topography of the ocean floor. They use that knowledge to find their way around without having to rely on their ability to echo-locate using sound.
What is the difference between porpoises and dolphins?
Porpoises are generally smaller than dolphins. With the exception of the finless porpoise, they have a triangular dorsal fin (whereas most dolphins have a sickle-shaped fin). Porpoises also have different teeth; they are spade-shaped and look much more like our teeth, whereas dolphins have cone-shaped teeth (which looks like an upside-down ice-cream cone). Dolphins can…
What makes porpoises interesting to study?
Porpoises are enigmatic little creatures. We know very little about them as they spend most of their lives underneath the ocean surface. We usually only observe them when they surface to breathe, and just about 5% of what they do happens above the surface. That means we have countless questions and very few answers, and…
Why are Dall’s porpoise hunted in Japan?
In Japan, thousands of Dall’s porpoise are killed in directed hunts every year. The animals are killed for consumption. As there are no recent abundance estimates for Dall’s porpoise in Japanese waters, it is unknown whether the take is sustainable, i.e. whether it is having any negative effects on population trends. In addition to directed…
Why is by-catch in fishing nets an issue for porpoises?
Accidental by-catch in fishing nets is estimated to kill 300,000 whales, dolphins and porpoises every year. Porpoises are air-breathing mammals, so once they become stuck in a net, they only have minutes before they drown. Active fishing gear is just as dangerous as abandoned gear. “Ghost nets”, forgotten or abandoned at sea by fishermen, are…
Why is the vaquita endangered?
The single most serious thread to the vaquita, and the cause for its rapid decline, is the use of gill-nets in the vaquita habitat.
A gill-net is a wall of netting that hangs in the water column. The mesh is designed so that fish can get their heads through, but not the rest of their bodies. As they struggle to free themselves, they get entangled with their gills. Gill-nets are very effective and used around the world, but often lead to large amounts of by-catch and pose a threat to other marine animals, such as sea turtles, seals and sea lions and cetaceans like the vaquita. If a vaquita gets entangled, it only has minutes to free itself. Most animals drown, and those that escape often do so with severe injuries.