Working together to keep today's treasures for tomorrow slide image Protecting the natural heritage of this diverse estuary slide image Promoting water quality and land preservation slide image Supporting a rich ecosystem for our local economy and quality of life slide image Managing our natural resources through consensus building slide image

News and Resources

Appreciating Skates and Rays in our Coastal Bays - July 20, 2014

Flying through the water on wings with no feathers, skates and stingrays are some of the most beguiling animals in the world. There are over 500 species of skates, rays and their cousins worldwide and they come in a wide variety of shapes, sizes, and color patterns. They can be found in many major oceans, bays, lagoons and even in freshwater ecosystems like large rivers. Skates and rays are truly intriguing animals that have evolved perfectly to fit their aquatic habitats. 

Skates and rays belong to the Class Chondrichthyes, or cartilaginous fish. This class also contains other related cartilaginous fish such as sharks, sawfish, guitarfish, and angelfish. Within this class, skates and rays belong to the Superorder Batoidea, and within that they belong to four different orders; Order Myliobatiformes are the stingray and its relatives, the order Rajiformes are the skates and its relatives, the order Torpediniformes are the electric rays and finally the order Pristiformes contain sawfish. 

Skates, rays and their relatives have evolved many unique adaptation traits that allow them to thrive in almost any aquatic ecosystem. Skates and rays are dorsoventrally flattened which means that they are flat and wide, not streamlined like many fish. They have evolved to have extremely large pectoral fins connected directly to their head, which they use primarily for swimming and digging themselves into soft substrates, however they have also lost the true anal fin, which many fish have. 
    
Skates and rays have evolved so their gill slits are on the bottom of their body, near their mouth. Because skates and rays are benthic animals, they spend a large portion of their time buried in or laying on the bottom of oceans, bays and rivers looking for food or for protection. This means that their gill slits are often firmly pressed into sand, silt and other substrates so in order to draw in clean water they use appendages called spiracles, located on the top of their body, often directly behind their eyes. These spiracles are often confused for eyes because they are usually round, and only an inch or two wide in most skate and ray species. Spiracles are basically tubes with an opening and flap on the top of the animal that allows for clean, oxygenated air to be taken in from above, then passed over the gills and then expelled out via the gill slits on the bottom of the animal.

Because skates and rays look similar to the untrained eye, they are often mis-identified by the general public and even some avid fisherman, however there are a few minor differences which help to tell the two groups apart. Skates in general have wider, thicker, fleshier tails than stingrays with some small fins located just near the base of the tail. Stingrays have a poisonous barb located at the base of their tail however skates lack this barb but may have spines or thorny projections present to help protect them. In general body shape, skates and rays differ slightly as well; Stingrays tend to have a diamond or kite like body shape, while rays are more round or triangular shaped with a more elongated and pointy “nose,” the front of the body forward of the eyes, spiracles and mouth. 

The biggest difference between skates and rays is their reproductive cycle. Stingrays are oviviparous, which means that they have internal fertilization however their young are raised internally within an egg and hatch within the mother before being born, as opposed to humans where the fetus is attached via a placenta to the mother and is not encased in a protective egg. 
Skates on the other hand are oviparous, which means that they still have internal fertilization, however they lay tough, keratinized egg cases, which they attach to substrates or other objects, which then grow and hatch outside of the females body. After laying the fertilized eggs, adult skates will then swim away, providing no parental care for the eggs or newborn skates after the initial egg laying. 

Both forms of reproduction result in the newborn animal being fully developed and a miniature version of the parent, without having to go through several larval or planktonic stages, as is the case in many fish or crustaceans. This means that a new-born skate or ray can swim, actively hunt and avoid predators only moments after being born or hatched. 

Here in the Coastal bays, we have several species of skates and rays that can be found from the shallow, brackish waters of the back bays to the crashing surf off the coast of Ocean City and Assateague. Cow nosed Stingrays are commonly seen throughout the bays and sometimes move in large groups looking for some of their favorite food, hard shelled clams. Other common ray species in the coastal bays include the Smooth Butterfly Ray, Spiny Butterfly Ray, the Bullnose ray, and the Southern Stingray. Clearnose Skates are commonly caught by surf fisherman on our local beaches, and many beach goers find skate egg cases washed up on our beaches as well.  

Harrison Jackson is the Coastal Stewards Coordinator for the Maryland Coastal Bays Program. 



Archived News

More Archived News
View Current News

U.S EPA News Region 3

Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program
Coastal Bays Program