Male anglerfish are much smaller than females. On average, male anglerfish are 4 to 6 inches long, while the largest females grow between 3 to 4 feet. Also, males lack many of the female's most prominent characteristics such as large teeth, the dorsal spine that creates the female's "angler," and dorsal spines. Males have proportionately larger noses, though, which enable them to find females for mating. Females release chemicals known as pheromones; male anglerfish use their nose to determine the whereabouts of females. Like females, male anglerfish have dark gray or black scales.
All deep sea anglerfish live at the bottom of the Atlantic and Arctic Oceans, near the coastlines of Great Britain, Scandinavia and Western Europe. Some specimens live up to a mile underneath the water's surface. However, some deep sea anglerfish live in the tropical waters of the Mediterranean Sea. Many male deep sea anglerfish live in complete darkness and extremely cold water temperatures; the temperatures at the bottom of the ocean range from 28 degrees to 35 degrees Fahrenheit. To conserve energy, these fish do not move rapidly. Anglerfish have infrared vision to see in their dark surrounds; however, these fish rarely use their eyes.
Male deep sea anglerfish experience a deterioration of their digestive system once they reach maturity. This prompts male deep sea anglerfish to find females. Males use their small teeth to latch on to females. Once they latch on to the female, males act as parasites and feed off the much larger female anglerfish. Up to six male anglerfish are able to feed off one female.
Since males rely on females for nourishment, they are readily available when the time comes for females to spawn. Males fuse their bodies with the female's body in an act of "sexual suicide." The male and female's blood systems and organs unite as one. Only the male's testes remain once the fusion is complete. As a result, females will have male and female sexual organs. This is advantageous to the female anglerfish since encounters with males are rare, according to Wayne P. Armstrong at Palomar College. Similarly to feeding, females are able to accommodate six male testes at one time.