Education

Biological Profiles

Education Selections... South Florida Aquatic Environments About the Different Groups of Fishes About the Anatomy of Fish and Sharks How Fish and Sharks Swim About Fish Adaptations About the Endangered Species Act How to Become a Biologist About Careers In Ichthyology Most Commonly Asked Shark Questions Most Commonly Asked Sawfish Questions Most Commonly Asked Ray and Skate Questions Most Commonly Asked Fish Questions Identification Key to Freshwater Fishes of Peninsular Florida Field Key to Sharks Skates of the Western Gulf of Maine Project Shark Awareness - A Public Outreach Educational Program Shark Fishing in U.S. Territorial Waters Most Commonly Asked Sawfish Questions Sawfish In Peril - PowerPoint file Sawfish Informational Brochure - Acrobat file Sawfish Outreach Boat Ramp/Marina Sign - Acrobat file Sawfish In The News Sawfish References Sawfish Links Smalltooth Sawfish species profile Largetooth Sawfish species profile Green Sawfish species profile Freshwater Sawfish species profile Dwarf Sawfish species profile Knifetooth Sawfish species profile Chondrichthyes Bibliography Search Freshwater Fishes of Florida References General Fish References Shark References Sawfish References Childrens' Shark Books Stingray Reproduction References Biological Profiles Glossary of Terms Shark Games: Test Your Knowlege! 2003 Open House Photos SMOOTH BUTTERFLY RAY Order - Rajiformes Family - Gymnuridae Genus - Gymnura Species - micrura Taxonomy Bloch and Schneider first described the smooth butterfly ray in 1801. The genus Gymnura of the currently accepted scientific name is derived from the Greek word gymnos meaning naked. Synonyms for Gymnura micrura include Pteroplatea micrura, Raja micrura and Gymnura micura. Common Names Common English names for this species include: lesser butterfly ray, diamond skate, butterfly ray, short-tailed lesser butterfly ray, and skeete. Other names include arraia (Portuguese), gladde vlinderrog (Dutch), korthalet sommerfuglerokke (Danish), krídloun hladký (Czech), motýlovec hladkýpari (Czech), gampret (Malay), perhosrausku (Finnish), raie-papillon glabre (French), raya guayanesa (Spanish), raya mariposa menor (Spanish), togenashi-tsubakuro-ei (Japanese), and uge-borboleta (Portuguese). Geographical Distribution The smooth butterfly ray is found in the western and eastern Atlantic Ocean and in the Gulf of Mexico. In the western Atlantic it occurs from Maryland to Brazil. It occurs in the Gulf of Mexico and northern South America to Brazil. It also occurs in the eastern Atlantic off the coasts of Senegal, Gambia, Sierra Leone, Cameroon and Democratic Republic of the Congo (to the mouth of Congo River). World distribution map for the smooth butterfly ray Habitat The smooth butterfly ray prefers neritic waters of the continental shelf and is usually found on soft bottoms. This species is known to enter brackish estuaries or hyper-saline lagoons. Biology Smooth butterfly ray: dorsal and ventral views © George Burgess · Distinctive Features This is a broad, diamond-shaped ray with a very short tail lacking a dorsal spine and a protruding snout. The front edges of the disk are concave. The tail has low dorsal and ventral finfolds and three to four dark crossbars. Smooth butterfly ray front disk edges are concave © Christina Conrath This ray can be distinguished from the spiny butterfly ray (G. altavela) by the absence of both a tentacle like structure protruding from the inner posterior margin of the spiracle and a caudal fin spine. The absence of a tail spine and the presence of a keel on the upper surface of the tail separates G. micrura from G. hirundo. The dorsal surface of this ray varies greatly in color, either gray, brown, or light green © Christina Conrath · Coloration The dorsal surface of this ray is gray, brown or light green, dotted and vermiculated with paler and darker spots. The tail has three to four dark crossbars. The ventral surface is white. This species has some ability to adapt it's shade to that of the bottom. ·Dentition The upper jaw generally has 60 to 120 teeth and lower jaw generally has 52 to 106 teeth, with each tooth having one short sharp conical cusp on a somewhat swollen base. Eight to nine rows of teeth function simultaneously. The upper dental plate occupies 70 to 75% of the width of the jaw and the lower dental plate occupies 60 to 65% of the width of the jaw. ·Denticles The skin is relatively smooth with small denticles. Smooth butterfly rays grow to a maximum disk width of 3-4 feet © George Burgess ·Size, Age, and Growth The maximum disc width of the species is reported to be 3 to 4 feet (0.9 to 1.2 m). Females of the northwestern Atlantic population pup when 25 inches (65 cm) wide, and probably at smaller lengths. · Food Habits Feeds on fish and invertebrates, more specifically: bony fish, benthic copepods, crabs, shrimps, prawns, and bivalves. · Reproduction Exhibits ovoviparity (aplacental viviparity), with embryos feeding initially on yolk, then receiving additional nourishment from the mother by indirect absorption of uterine fluid enriched with mucus, fat or protein through specialized structures. · Predators Potential predators include larger fishes and marine mammals. Importance to Humans This species is caught in minor commercial fisheries and is occasionally used for food in French Guiana and possibly in other tropical localities. The wings may be taken for bait in crab or other fisheries. Smooth butterfly rays are caught in minor fisheries © George Burgess Danger to Humans This is a small ray that does not possess a spine. Therefore it represents little danger to humans. Conservation This ray is not listed as endangered or vulnerable with the World Conservation Union (IUCN). The IUCN is a global union of states, governmental agencies, and non-governmental organizations in a partnership that assesses the conservation status of species. Prepared by: Christina Conrath