Southern Stingrays & Stingray ...
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& Stingray City
Name Change
You may see this species listed as Dasyatis americana in older research. The accepted name is now Hypanus americanus per the World Register of Marine Species. The term "Southern Atlantic stingray" sometimes appears online but is not used by scientists - and it can cause confusion with the Atlantic Stingray (Hypanus sabinus), which is a completely different species.
| Measurement | Female | Male |
|---|---|---|
| Max Disc Width | 150 cm (59") | 80 cm (31") |
| Max Weight | ~134 kg (295 lbs) | ~13 kg (28 lbs) |
| Size at Maturity (Wild) | ~76 cm (30") | ~57 cm (22") |
| Age at Maturity (Captive) | 5 - 6 years | 3 - 4 years |
| Max Lifespan (Captive) | ~30 years | ~8 years |
Cartilage, Not Bone
Like sharks, their entire skeleton is made of cartilage (the same flexible material in your ears and nose) instead of bone. They also lack a swim bladder - instead, a large oily liver (over 50% of the body cavity when healthy) helps with buoyancy.
Flat Body Design
Their body is flattened from top to bottom with fins fused to the head, forming the disc shape. Eyes and breathing holes (spiracles) sit on top so they can see while lying on the sea floor. The mouth and five gill slits are underneath.
Venomous Tail Barb
One or more serrated spines on the tail contain venom glands in two grooves on the underside. A thin skin sheath covers the barb and ruptures on contact, releasing the toxin. Backward-facing teeth make removal difficult.
How They Eat
Unlike sharks with their sharp teeth for tearing, stingrays have flat, plate-like teeth built for crushing. Their jaw is highly flexible, allowing complex chewing motions that can break down hard shells like crabs and clams.
Suction feeding is their main technique - they rapidly expand and contract their mouth cavity to vacuum up prey and sand from the sea floor. They also shoot jets of water from their mouths to blast buried prey out of the sand.
Researchers have documented over 21 different foraging behaviors across five stages: searching while swimming, settling on the bottom, searching on the bottom, sucking up prey, and then either taking off, resting, or burying into the sand.
What They Eat
Opportunistic meat-eaters going after whatever is available. Scientists used two methods to work out their diet - flushing the stomach for recent meals, and analysing body tissue chemicals for long-term patterns:
| Recent Meals (Stomach) | Long-Term Diet (Tissue) |
|---|---|
| Shrimp & crabs: 89% | Clams & shellfish: 47% |
| Small fish: remainder | Worms: 19% |
| Shrimp & crabs: 16% | |
| Small fish: 16% |
Behavior & Senses
- Loners by nature - normally solitary; large groups only form where humans feed them
- Night hunters - most active at dawn and dusk in the wild
- Homebodies - return to the same areas; females stick closer to home than males
- Smart navigators - move purposefully toward targets within 100 m, using patch reefs as landmarks
- Hearing - sense vibrations in the water (not sound pressure); females hear better than males, improves with age
- Magnetic sense - can detect and avoid magnetic fields
Mating
- Females don't have a fixed breeding season - they can mate and give birth at any time of year
- They mate with multiple males, and a single litter can have 2-3 different fathers
- Females may mate within minutes to hours after giving birth, meaning they may be pregnant for most of their adult lives
- The mating process has five steps: the male follows the female, bites her fin to hold on, they mate belly-to-belly, rest, then separate
- Females have been seen poking males with their tail barb during mating
Pregnancy & Birth
- Uterine milk - after the embryo uses up its yolk sac, finger-like structures in the uterus wall called trophonemata secrete a rich nutrient fluid that feeds the baby
- Females have only one working ovary (the left side) - the right side is there but does not function
- Young stingrays grow up in mangrove estuaries as nursery habitats, then move to deeper offshore areas once they reach about 58 - 70 cm disc width
- Their diet does not change much as they grow - they eat the same types of food at every size
The Venomous Barb
The barb is a hard, sharp spine at the base of the tail with backward-facing teeth (like tiny fishhooks) and venom glands underneath.
- A sting causes immediate, intense pain that peaks within 30-90 minutes and can last up to 48 hours without treatment
- Best treatment: soak the wound in hot water (as hot as you can handle without burning) for 30-60 minutes - heat breaks down the pain-causing component
- Infection is a risk from marine bacteria like Vibrio getting into the wound
- Prevention: shuffle your feet when wading in shallows to give nearby rays a chance to move away
Their Protective Mucus
The slimy coating on their skin does far more than reduce drag - scientists found it is chemically similar to what we call stingray "venom."
- Fights infection: The mucus stops fungal growth and contains 26 proteins related to immunity
- Unique bacteria: Their skin carries bacteria completely different from the water around them, including types that produce natural antibiotics
- Causes swelling: If it gets into a wound, it triggers inflammation and swelling
- This mucus layer is especially important for healing the bite wounds females get during mating
Fishing & Bycatch Threats
A study in Cuba found 300 stingrays caught accidentally in shrimp trawling nets over 14 months - 61% were female and 41 of them were pregnant, carrying 87 unborn pups between them. In Brazil, stingray meat sold at fish markets was found to have mercury levels above safe limits for human consumption, mostly in the more dangerous methylmercury form.
Fishermen have been cleaning their catch in this area since the 1930s, which attracted stingrays looking for scraps. In 1986, tour operators began deliberately feeding the rays and moved the activity to a shallow sandbar where tourists could stand in the water. By 2006, as many as 3,000 visitors were arriving in a single day.
The population is heavily skewed - over 80% are adult females. The Grand Cayman stingray population is genetically isolated and distinct from other Caribbean populations. Despite being wild animals, they now grow at rates similar to aquarium stingrays due to the constant food supply.
The Guy Harvey Research Institute runs surveys twice a year - counting rays, tagging individuals, measuring growth, and checking for pregnancies. By end of 2024, 67 surveys had been done over 22 years.
Tracking Methods
- PIT Tags - tiny microchips injected under the skin (like pet ID chips) to identify individuals over time
- Acoustic Transmitters - small sound-emitting devices attached to rays, picked up by underwater receivers to map movement
- Tail Muscle Tags - a newer method that stays attached for up to 212 days and heals completely after removal
Behavioral Changes
- Day/night flip - wild stingrays are active at night, but fed stingrays have switched to daytime to match tourist feeding schedules
- Tiny home range - wild females roam an area at night roughly 45 times larger than what fed females use during the day
- Forced together - fed rays' living spaces overlap by 72%, compared to just 3% for wild solitary populations
- Never leave - 94% of tagged stingrays were recaptured at the same site; 20% of females stayed for 10+ years
- Isolated gene pool - almost no movement between the feeding site and wild populations, raising concerns about inbreeding
Health Costs
- Signs of anemia - lower red blood cell counts and blood protein levels than wild stingrays
- Cell damage - higher oxidative stress, linked to premature aging
- Weakened immunity - white blood cell profiles suggest their immune systems are suppressed
- Boat injuries - 12% of fed rays have propeller scars vs. 0% in wild populations
- Crowding injuries - 85% of females at the tourist site were injured vs. 30% elsewhere; 100% had bite marks from other stingrays competing for food
- More parasites - 98% carry blood-feeding skin parasites, with 30% more parasites than wild rays
Ecological Trap
Scientists describe Stingray City as an "ecological trap" - the easy food draws stingrays in, but the long-term costs (stress, weaker immune systems, injuries, parasites) may actually shorten their lives. The fed rays also show significantly lower body condition than wild ones, and some have developed open, bleeding skin lesions never seen in wild populations - possibly from contact with human pathogens, sunscreen chemicals, or the unnatural diet.
Wrong Food Entirely
The squid fed to tourists (Loligo opalescens or Illex sp.) is shipped from the North Atlantic and North Pacific. Squid is not a natural food for Southern Stingrays - they normally eat crustaceans and shellfish from the sea floor.
Wrong Nutrients
The squid creates an unnatural balance of essential fatty acids - fats that are critical for fighting disease, handling stress, and healthy reproduction. Their body chemistry now resembles cold-water animals rather than tropical ones.
Season Matters
In October (fewer tourists), the rays eat more natural wild prey. In January (peak season), both males and females show similar body chemistry, suggesting they are both relying heavily on tourist-provided squid instead of foraging naturally.
Boat Permit Rules
- Permit runs January 30 to January 30 each year
- Only 1 crew member per boat may feed the stingrays
- Max 1 lb of approved food per trip (ballyhoo or squid only)
- Max 100 passengers per trip, regardless of vessel size
- Max 1,500 people in the water on the sandbar at one time
- Max 20 tourist boats anchored at the sandbar
- 1-hour anchor limit per boat
- Sandbar closed weekends after 14:00, public holidays after 15:00
Approved Interactions
- Stroke the wings (pectoral fins) on top or underneath while a crew member holds the ray or as it swims past
- Cradle the ray flat in the water with bent arms, nose facing toward you (keeps the tail safely away)
- Briefly angle the nose up for a "kiss" - but the eyes, mouth, and spiracles must stay underwater
- Use reef-safe sunscreen (zinc oxide or titanium dioxide) and apply it well before getting in the water
- Simply watch without touching - hands-off observation is perfectly fine
Prohibited Actions
- Lifting the ray so its gills, mouth, spiracles, or eyes leave the water - illegal because it stops the ray from breathing
- Bending any part of its body (back or wings) - this causes internal and skeletal damage
- Touching the center of the body (back or belly) or the base of the tail - these areas cover vital organs
- Gripping or pinning the fins - the stingray must always be free to swim away
- Holding it so its wing slaps against your body ("back slaps") - this is no longer allowed
Legal Protection
Under the Cayman Islands National Conservation Law (2013), all sharks and rays are classified as "Species Protected at All Times" - the highest level of legal protection. It is illegal to take, possess, sell, injure, or disturb any stingray. Stingray City is a designated protected area with additional restrictions. Even wearing gloves while diving or snorkeling in Cayman waters is an offense.
What Research Recommends
Scientists built a computer model that simulated 25 years into the future under different management plans. They also surveyed tourists and found two main groups:
- Doing nothing makes it worse - without changes, stingray health and the tourist experience both decline over time
- Best plan: a balanced approach - fewer visitors at a time, less handling and feeding, better quality food, and a small conservation fee
- Quality beats quantity - the most successful scenarios produced healthier stingray populations and better visitor satisfaction, attracting tourists who value conservation
A Note on Steve Irwin
Steve Irwin was killed on 4 September 2006 by an Australian bull ray (Myliobatis australis) - a completely different family of ray (Myliobatidae) than the Southern Stingray's family (Dasyatidae), found only in Australian and New Zealand waters. The cameraman on scene said the ray "probably felt threatened" as it was boxed in between Irwin and the camera. The Southern Stingrays at Stingray City are a different species in a different ocean, and are well accustomed to human contact.
Guy Harvey Research Institute · IUCN Red List · Cayman Islands DOE