first discovered in porpoises. One of the first anatomical descriptions of the airways of the whales on the basis of a harbor porpoise dates from 1671 by John Ray. It nevertheless referred to the porpoise as a fish, most likely not in the modern-day sense, where it refers to a zoological group, but the older reference as simply a creature of the sea (cf. for example star-fish, cuttle-fish, jelly-fish and whale-fish). In captivity Harbour porpoises have historically been kept in captivity, under the assumption that they would fare better than their dolphin counterparts due to their smaller size and shallow-water habitats. Up until the 1980s, they were consistently short-lived. Harbour porpoises have a very long captive history, with poorly documented attempts as early as the 15th century, and better documented starting in the 1860s and 1870s in London Zoo, the now-closed Brighton Aquarium & Dolphinarium, and a zoo in Germany. At least 150 harbour porpoises have been kept worldwide, but only about 20 were actively caught for captivity. The captive history is best documented from Denmark where about 100 harbour porpoises have been kept, most in the 1960s and 1970s. All but two were incidental catches in fishing nets or strandings. Nearly half of these died within a month of diseases caught before they were captured or from damage sustained during capture. Up until 1984, none lived for more than 14 months. Attempts of rehabilitation seven rescued individuals in 1986 only resulted in three that could be released 6 months later. Very few have been brought into captivity later, but they have lived considerably longer. In recent decades the only place keeping the species in Denmark is the Fjord & Bælt Centre, where three rescues have been kept, along with their offspring. Among the three rescues, one (father of world's first harbour porpoise born in captivity) lived for 20 years in captivity and another 15 years, while the third (mother of first born in captivity) is still alive in 2021 after 23 years. This is older than the typical age reached in the wild, which is 14 years or less. Very few harbour porpoises have been born in captivity. Historically, harbour porpoises were often kept singly and those who were together often were not mature or of the same sex. Disregarding one born more than 100 years ago that was the result of a pregnant female being brought into captivity,