Comprehensive DescriptionRead full entry
Rays of the family Myliobatidae are well known for their extreme grace and great size. With three subfamilies containing seven genera and about 42 species, the family includes the eagle rays, manta or devil rays, and cownose rays (see Systematic/Taxonomic History). These are free-swimming rays with broad, powerful pectoral fins that can measure over 6 m from tip to tip (see Physical Description). Many members of the family are able to leap completely out of the water into the air. Rays, like their shark relatives (both fall within the superorder Euselachii), have a reproductive strategy in which a great deal of energy is invested in relatively few young over a lifetime, which may last several decades. Myliobatids generate, depending on the subfamily, only one to six embryos each year, and these young are born live after growing to considerable size inside the mother’s uterus (see Development, also Reproduction). Despite the imposing size attained by many members of the family, these rays are not dangerous to humans. Mantas have tiny teeth and strain planktonic organisms (and sometimes small schooling fishes) from the water. Eagle and cownose rays have pavement-like teeth suited for grinding mollusks (see Food Habits). Their tail spines, when present, are used for defense. The worst damage caused by these rays is economic, for they are capable of destroying entire beds of cultivated mollusks or oysters (see Economic Importance to Humans). As of 1994 only one species was listed as vulnerable to extinction, but due to their “slow” reproductive strategy rays may have difficulty replenishing their numbers if human activity threatens them.