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cartilaginous fishes
Class Chondrichthyes
This class comprises the sharks, rays, skates, and chimaeras. In the salt marsh-tidal creek system you will find a few different species of sharks and rays. They are characterized by having jaws and a skeleton made of cartilage, like what our ears are made of, instead of bone. Instead of having an operculum covering their gills, sharks and rays have 5-7 visible gill slits on the sides of their head. Unlike bony fish, the cartilaginous fish do not have a swim bladder, so must move continuously or else they will sink.
One characteristic unique to cartilaginous fishes is the ampullae of Lorenzini. If seen, the ampullae will look like small dots around the mouth or nose of a shark or ray. They are actually sensory cells that are able to detect small electric charges given off by their prey. These animals are not naturally aggressive, but when walking through a tidal creek it may be a good idea to do the “sting ray shuffle” to warn them that you are coming.
Atlantic stingray
Dasyatis sabina
Trophic Level: Carnivore
Characteristics: disk-shaped, flat body, dark gray or light brown above and lighter below; snout is elongated
Range: NJ to the Gulf of Mexico
Size: up to 2ft (.5m) in disk width
Habitat: shallow estuaries, tidal creeks
Fun Fact: spiracles on the top are often mistaken for another set of eyes but they actually take in water while buried in sediment
Where It's Found: Tidal creek
Atlantic sharpnose
Rhizoprionodon terraenovae
Trophic Level: Carnivore
Characteristics: streamlined body, gray dorsally and white ventrally; nose comes to a point, anal fin originates slightly in front of the second dorsal fin
Range: Atlantic coast of the U.S. to the Gulf of Mexico and Brazil
Size: up to 3.5ft (1m) in length
Habitat: surf zone of sandy beaches and into estuaries
Fun Fact: juveniles have black edges on dorsal and caudal fins
Where It's Found: Tidal creek
Bonnethead
Sphyrna tiburo
Trophic Level: Carnivore
Characteristics: shovel-shaped head with eye on either side; gray-brown dorsally and white ventrally; mouth on the bottom
Range: Atlantic coast of the U.S. to Brazil, and CA to Ecuador
Size: up to 4ft (1m) in length
Habitat: warm estuaries, often in tidal creeks
Fun Fact: females move further into shallow water than males do, but scientists do not yet understand why
Where It's Found: Tidal creek
