By Tom Baird
With warm weather and warm water, the bay is getting active. It is impossible to take a casual stroll in the sandy shallows of St. Joseph Bay now without seeing rays – rays quickly swimming away, rays feeding, and rays partially buried in the sand. The rays are prolific and are an integral part of the balance and ecology of the bay.
Rays that are commonly found in the bay are the Spotted Eagle Ray (Aetobatus narinan), Cownose Ray (Rhinoptera bonasus), the Bluntnose Stingray (Dasyatis say), the Southern Stingray(Dasyatis americana),and the Atlantic Stingray (Dasyatis sabina). Rays are related to sharks and you often see them lumped together as sharks, skates and rays for ease of understanding their physiology. Like sharks and skates, rays are cartilaginous fishes, lacking true bone in their skeletons. Cartilage is the firm but flexible material at the tip of your nose, your ears, and the pads between your bones at joints.
It is the Atlantic Stingray that most people see gliding over or resting on the bottom in shallow water and it can be easily distinguished from other ray species because the snout is slightly elongated and pointed. It doesn’t attain a large size, only reaching a maximum length of about two feet. The range of the Atlantic stingray is from Chesapeake Bay around Florida and throughout the Gulf of Mexico and southward to the Bay of Campeche in Mexico. The adults are brown or pinkish brown on top and white below, and they are truly lovely to watch when they are slowly swimming, undulating their large pectoral fins.
These rays feed on organisms buried in the substrate such as worms, clams, and various crustaceans such as small crabs. They possess crusher teeth down in the throat called pharyngeal teeth, which they use to crush the shells of clams and other bivalves. These pharyngeal teeth are frequently found in Indian middens in Florida, demonstrating that early peoples caught them for food or for the serrated barb on the tail to use as a tool. Rays can inflict a painful bite if you are foolish enough to pry their mouths open to look at the pharyngeal teeth. (Yes, it has happened to me.)
When rays detect the presence of prey, they will begin digging using powerful thrusts of their snout and flapping their large pectoral fins to push away the sand and mud. With a little patience, it is easy to observe this feeding activity by either standing very still or sitting quietly in a kayak. When they have taken the prey, they will often leave sizeable pits or depressions in the sand. All those craters in the sandy shallows are left by hunting and feeding stingrays. The rays themselves are not without predators. Bull sharks and Tiger sharks eat stingrays.
Atlantic stingrays can tolerate various salinities and can travel between the open Gulf into bays and estuaries. An unusual characteristic of this ray is that it can even live in fresh water. Atlantic stingrays inhabit the St. Johns River here in Florida and there is even a freshwater population in Lake Jesup in Seminole County in central Florida.
Of course, what most people think of at the mention of stingrays is their ability to defend themselves with a quick flip of the tail. A serrated barb covered in venomous slime is not at the tip of the tail, but about half way down the long, whip-like tail. The slash or puncture wound that it inflicts is painful, but rarely life threatening. Plenty of folk remedies abound, but it is best to simply get to a hospital for medical attention. There have been cases of prolonged nerve damage from a ray’s venom. The usual precaution is to shuffle your feet and warn the buried rays of your approach. They want to get away from you as fast as they can. Despite the fear of rays, wounds from rays are rare, although this varies by location. Some tourist beaches abound with rays. About 1,500 stingray-induced injuries occur in the United States annually, although there is likely a degree of under-reporting due to self-treatment.A prominent local kayak outfitter and eco-tour operator on Cape San Blas has never had a customer injured by a ray in twenty years. Considering both the number of rays in the water and the number of tourists wading and snorkeling, it is a testament to the fact that injuries from rays are relatively rare.
Less seen and known are the closely related Skates. Skates look very much like rays, but generally inhabit deeper waters. We have plenty offshore here and you have probably seen their egg cases washed up on the beach. If you have seen the black leathery tubes with hooks at each corner scattered on the beach, these are the protective egg cases of skates. They are called Mermaid’s Purse, and are frequently collected by beach goers.
While skates reproduce by laying eggs, our little Atlantic stingray delivers live young. After mating, the developing embryos are nourished by a yolk sac much like a reptile or bird egg. However, after about two months, the little developing rays are nourished by a uterine milk secreted by the mother. By late summer, July to August, the female rays give birth to litters of up to four stingray pups, which are miniatures of the adults and ready to fend for themselves.
Despite the fear of rays, they are smart, curious animals, and can be easily taught to be hand-fed and held. Resorts in the Caribbean have made tamed rays a photo experience for tourists. Nevertheless, the rays of St. Joseph Bay can delight us, whether we are watching a pair of Cownose Rays swimming slowly together near the beach or observing from a boat as a spectacular Spotted Eagle Ray glides in deep water, or watching the common Atlantic stingray burrow for its dinner of clams and worms. These animals deserve our respect and protection.
Tom Baird has been a fisheries biologist, high school and community college teacher (oceanography and microbiology), director of a science and environmental center, teacher of science and principal in Pinellas County as well as an educational consultant. He retired from the Florida Department of Education and he and his wife divide their time between Tallahassee and Cape San Blas.