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Biological Profiles
BLUNTNOSE STINGRAY
Order - Myliobatiformes
Family - Dasyatidae
Genus - Dasyatis
Species - say
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Taxonomy
The bluntnose stingray was originally named Raja say by Lesueur in 1817. Although Dasyatis sayi
Lesueur 1817 appears frequently in scientific literature in reference to this species, the currently valid name
is Dasyatis say (Lesueur, 1817). The genus Dasyatis is derived from the Greek word "dasys" meaning
rough or dense and "(b)atus" meaning shark. The bluntnose stingray is a member of the family Dasyatidae, commonly
known as the "whip-tailed" rays.
Common Names
In the English language, Dasyatis say is usually referred to as the bluntnose stingray or Say's stingray.
In other languages, common names include arraia-manteiga (Portuguese), manteiga (Portuguese), raia (Portuguese),
or raia amarela (Portuguese); stumpfnasenstechrochen (German); stompsnuitpijlstaartrog (Dutch); and raya mediana
(Spanish), raya hocicona (Spanish), and raya (Spanish).
Geographical Distribution
Although uncommon in occurrence, the bluntnose stingray can be found in the western Atlantic from New Jersey and
Massachusetts in the United States. It also resides in the northern Gulf of Mexico as well as off the coasts of
Argentina, Brazil, and Uruguay in South America. This species is widespread throughout the West Indies and the
Antilles. However, there have been no recorded findings of this stingray along the coasts of Mexico, Columbia,
Venezuela, or Central America.
World distribution map for the bluntnose stingray
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Habitat
The bluntnose stingray prefers subtropical coastal waters, lagoons, and estuaries (41°N-40°S). This species resides near
the shoreline in waters to 33 feet (10 m) in depth and appears to be most active at night during spring and fall,
as indicated by their increased capture rate. These rays are not found in fresh water, preferring high salinity of
25-43 parts per thousand (ppt) over brackish environments. Bluntnose stingrays prefer water temperature ranging from
54°F-91°F (12°C-33°C). Adults are more commonly found in depths greater than 3 feet (1 m). This stingray spends
large amounts of time buried in mud flats or sand with only the eyes and spiracles exposed. During the winter, in
northern regions of their distribution, bluntnose rays migrate from coastal areas into estuaries.
Biology
- · Distinctive Features
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Juvenile bluntnose stingray ©
George Burgess
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The bluntnose stingray is a moderately sized stingray characterized by a distinctively blunt snout. Its lozenge-shaped
disk has rounded corners with few tubercles and spines along the midline. This species has a highly developed fold on
its dorsal surface and on the ventral surface of its long whip-like tail.
A. Bluntnose stingray and B. Atlantic stingray
courtesy NOAA
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Other species that are similar in appearance to the bluntnose stingray include the Atlantic stingray
(Dasyatis sabina). However the disk shape differs greatly between the two species and can be
used to avoid confusion (see figure above).
Bluntnose stingray: ventral coloration
© George Burgess
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- · Coloration
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Dorsal coloration varies from yellowish to light brown. Ventral coloration ranges from white to light gray.
A. Upper right-hand tooth band from female bluntnose
stingray, B. Upper left-hand tooth band from male bluntnose stingray (Fishes of the
Western North Atlantic, 1948)
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- ·Dentition
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The upper jaw of the bluntnose stingray protrudes slightly at symphysis while the lower jaw is indented, leading
to a slight overbite. Thirty-six to fifty rows of teeth are located in the upper jaw. The bottom of the mouth has
a cross row of three wide papillae with a lone, small papilla on each side. Each tooth has a quadrangular base.
During the mating season, adult male teeth develop wide, triangular cusps for grasping during copulation. Females
and juveniles have rounded cusps.
- ·Denticles
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Dermal denticles, characteristic of elasmobranchs, are less developed in Myliobatiformes. A row of
tubercles with crest sloping anteriorly are present along the mid-line of the dorsal surface of bluntnose stingray.
As the ray grows it develops 1 to 2 short rows of large tubercles on each shoulder. Mature individuals have small
prickles present on the dorsal surface anterior to the eyes and along the outer posterior parts of the disc.
- ·Size, Age, and Growth
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Bluntnose rays are known to be as large as 39 inches (100 cm) in disk width (DW). Females are slightly larger than males,
usually reaching maturation at 19.7-23.6 inches (50-60 cm) DW and 15.4- 33.1 pounds (7-15 kg). Males have a disk
width of 11.8-15.7 inches (30-40 cm) and weigh 6.6-13.2 pounds (3-6 kg) when mature.
- · Food Habits
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The diet of the bottom-feeding bluntnose stingray consists mainly of small bivalves, crustaceans, and annelid worms.
Additional prey include gastropods, amphipods, shrimps, fish, and crabs.
- · Reproduction
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The bluntnose stingray, like all stingrays, is ovoviviparous, with embryos receiving nourishment from
yolk and uterine secretions. Mating occurs each spring in a well-defined breeding period, with copulatory
activity peaking in May. Uterine eggs can be found from June until March. The gestation period lasts approximately
9-10 months. It appears that the fertilized eggs exhibit a period of arrested development until the final months
of the gestation period (April-May). Birth occurs in mid to late May with litter size ranging from 1-6 young.
Newborns are approximately 5.9-6.7 inches (15-17 cm) in disk width (DW) and weigh 0.37-0.55 pounds (170-250 g).
Most females reproduce on an annual basis. The bluntnose stingray has not been observed engaging in mating
rituals or courtship.
Bull sharks are known predators of the bluntnose
stingray © Doug Perrine
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- · Predators
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Large fishes including sharks such as the bull shark (Carcharhinus leucas) are known predators of the bluntnose stingray.
Importance to Humans
The bluntnose stingray is important to the tourist industry because of its popularity among snorkellers and
scuba divers. This stingray's venomous spine is also the subject of ongoing research in the biomedical and
neurobiological fields.
A. Tip and B. middle of a tail spine taken from a male
bluntnose stingray (Fishes of the Western North Atlantic, 1948)
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Danger to Humans
The bluntnose stingray is non-aggressive and poses little threat to humans. However, it will use its spine in
self-defense when stepped on. To avoid this, one can shuffle his or her feet while wading in shallow waters.
Conservation
The World Conservation Union (IUCN) does not consider the bluntnose stingray to be a threatened or endangered species.
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:
Jason Collins
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