Cetacea Cetacea Cetacea () is a widely distributed and diverse clade of aquatic mammals that today consists of whales, dolphins, and porpoises. Cetaceans are carnivorous and finned. Most species live in the sea, some in rivers. The name is derived from the Latin "cetus" "whale", itself from the Greek κῆτος "kētos" "huge fish". There are around 89 extant species, which are divided into two groups or parvorders, the Odontoceti or toothed whales, a group of more than 70 species that includes the dolphins, porpoises, belugas, narwhals, sperm and beaked whales, and the Mysticeti or baleen whales, of which there are now
Ultrasound whistle is a whistle that emits ultrasound, used for training and calling dogs. The frequency of most dog whistles is within the range of 23 to 54 kHz. Toothed whales, including dolphins, can hear ultrasound and use such sounds in their navigational system (biosonar) to orient and to capture prey. Porpoises have the highest known upper hearing limit at around 160 kHz. Several types of fish can detect ultrasound. In the order Clupeiformes, members of the subfamily Alosinae (shad) have been shown to be able to detect sounds up to 180 kHz, while the other subfamilies (e.g. herrings) can hear