- Streamlined body for efficient swimming.
- Cartilaginous skeleton, making them lightweight and flexible.
- Dorsal fins (usually two) for stability and maneuverability.
- Anal fins (usually one or two) for balance and stability.
- Pectoral fins (paired) and pelvic fins (paired) for steering, maneuvering, and balance.
- Caudal fin (tail fin) for propulsion.
Head and mouth:
- Blunt or pointed snout, depending on the species.
- Ampullae of Lorenzini, sensory organs near the snout, used to detect electrical fields.
- Large, powerful jaws, with several rows of teeth.
- Teeth are not fused to the jawbone but rather embedded in soft tissue, allowing for continuous replacement.
- Jaws can be protruded and retracted, facilitating a powerful bite.
Skin and coloration:
- Skin covered with dermal denticles, which are small, tooth-like scales.
- Coloration varies depending on the species, but generally consists of shades of gray, blue, brown, or green.
- Countershading is common, with darker colors on the upper side and lighter colors on the underside, providing camouflage.
- Some sharks have distinctive patterns, stripes, or markings.
Size:
- Sharks range in size from the smallest species, the dwarf lantern shark, which grows to a maximum length of about 6.5 inches (17 centimeters), to the largest species, the whale shark, which can reach up to 40 feet (12 meters) in length.
Teeth:
- Sharks have several rows of teeth, with new teeth constantly developing to replace lost or damaged ones.
- The shape and size of the teeth vary depending on the species and diet.
- Some sharks, like the great white shark, have large, serrated teeth for tearing flesh.
- Others, like the nurse shark, have smaller, blunt teeth for crushing shellfish and crustaceans.
Eyes:
- Eyes located on the sides of the head, providing binocular vision.
- Some species have nictitating membranes, also called third eyelids, which can be drawn across the eyes for protection.
Nostrils:
- Paired nostrils, located on the underside of the snout, used for smelling.
- Some sharks have nasal barbels near their nostrils, which help them locate food.
Spiracles:
- Some species have spiracles, which are small openings above the eyes, used for breathing.
- Spiracles allow sharks to breathe while lying on the bottom or in tight spaces.
Gill slits:
- Sharks have five to seven gill slits on each side of their head, used for respiration.
- Water enters the mouth, passes through the gill slits, and exits the body, allowing oxygen to be extracted.