1. Family Gymnuridae The Butterfly Rays
Greek, gymnos = naked + Greek,tai = tail

2. Descriptive Features Skin relatively smooth with small denticles
Broad, diamond shaped ray
DW is almost 2x TL
Short tail
Some with poisonous tail spine
Dorsal fin present or absent

3. Tooth Morphology

4. Order Myliobatiformes

5. Taxonomy 12-14 species in 2 genera
Aetoplata
A. zonura – Zonetail
A. tentaculata – Tentacled
Gymnura
G. australis - Australian
G. natalensis – Backwater
G. micrura – Smooth
G. altavela – Spiny
G. japonica – Japanese
G. poecilura – Long-tail
G. hirundo – Madiera (? validity)
G. bimaculata – Twin-spot
G. crooki
G. marmorata – California
G. crebripunctata – Long snout
G. afuerae

6. Gymnura debate G. marmorata G. afuerae G. crebripunctata
Gulf of California to Peru

7. Gymnura altavela over 4m wingspan (>13ft)
Largest Gymnura
Gymnura altavela over 4m wingspan (>13ft)

8. Found in the Atlantic, Pacific, and Indian Oceans
Distribution
Found in the Atlantic, Pacific, and Indian Oceans

9. Habitat Marine, rarely brackish Tropical to temperate
Continental shelves
Demersal, benthic
Depths range from intertidal to100m
Prefers sandy and muddy substrates
Also found in brackish estuaries, hyper-saline lagoons, coastal and neritic waters, bays, sandy beaches, and salt marshes

10. Diet Teleosts Crustaceans Mollusks Plankton Polychaetes
Benthic copepods, crabs, shrimps, prawns
Mollusks
Bivalves, cephalopods, gastropods
Plankton
Polychaetes

11. Predators
Marine mammals
Hammerhead sharks
Larger fishes

12. Reproduction Two functional uteri Aplacental viviparous
Embryos initially fed with yolk, then uterine milk
Gestation ~4-9 months
One reproductive cycle per year
Fecundity assumed to be <10
Females commonly abort fetuses upon capture (G. poecilura)

13. Status IUCN status Population doubling time >14 years
9 spp not in IUCN
3 spp data deficient
1 sp vulnerable – A. zonura (declines of at least 30%)
1 sp near threatened – G. poecilura
Population doubling time >14 years

14. Major Threats Bycatch (shrimp trawlers) Low recruitment/reproduction
High juvenile mortality
Habitat degradation and loss
Harvested for food
Food trade

15. Literature Cited
Bauchot, M.-L., Raies et autres batoides. p In W. Fischer, M.L. Bauchot and M. Schneider (eds.) Fiches FAO d'identificationpour les besoins de la pêche. (rev. 1). Mèditerranée et mer Noire. Zone de pêche 37. Vol. II. Commission des Communautés Européennes and FAO, Rome. 
Bizzarro, J.J. & White, W.T Gymnura poecilura. In: IUCN IUCN Red List of Threatened Species. < Downloaded on 28 November 2007.
Compagno, L.J.V., Checklist of living elasmobranchs. p In W.C. Hamlett (ed.) Sharks, skates, and rays: the biology of elasmobranch fishes. John Hopkins University Press, Maryland. 
Grubbs, R.D. & Ha, D.S Gymnura micrura. In: IUCN IUCN Red List of Threatened Species. < Downloaded on 28 November 2007.
Last, P.R. and J.D. Stevens, Sharks and rays of Australia. CSIRO, Australia. 513 p. 
McEachran, J.D. and B. Seret, Gymnuridae. p In J.C. Quero, J.C. Hureau, C. Karrer, A. Post and L. Saldanha (eds.) Check-list of the fishes of the eastern tropical Atlantic (CLOFETA). JNICT, Lisbon; SEI, Paris; and UNESCO, Paris. Vol. 1. 
Nelson, J.S Fishes of the World, 4th ed. John Wiley and Sons, Inc, NJ. p 80.
Smith, W.D. & Bizzarro, J.J Gymnura marmorata. In: IUCN IUCN Red List of Threatened Species. < Downloaded on 28 November 2007.
White, W.T Aetoplatea zonura. In: IUCN IUCN Red List of Threatened Species. < Downloaded on 28 November 2007.
Wintner, S.P Gymnura natalensis. In: IUCN IUCN Red List of Threatened Species. < Downloaded on 28 November 2007.
Gonzalez-Isais, M and Domı´nguez, HMM Comparative Anatomy of the Superfamily Myliobatoidea (Chondrichthyes) With Some Comments on Phylogeny. JOURNAL OF MORPHOLOGY 262:517–535.