1. Skeleton: Sharks have a cartilaginous skeleton, while humans have a bony skeleton. Cartilage is more flexible and less dense than bone, which gives sharks greater agility and maneuverability in the water.
2. Fins: Sharks have fins for movement and balance, while humans have limbs for walking and running. Sharks have a caudal fin (tail fin) that provides propulsion, pectoral fins (chest fins) for steering, and pelvic fins (hip fins) for stability.
3. Gills: Sharks have gills for extracting oxygen from water, while humans have lungs for extracting oxygen from air. Sharks have multiple gill slits on the sides of their heads, while humans have a single pair of nostrils.
4. Skin: Shark skin is covered in dermal denticles, which are small, tooth-like scales that give the skin a rough texture. This texture helps sharks reduce drag and improve their swimming efficiency. Human skin is smooth and flexible, with hair follicles and sweat glands.
5. Teeth: Sharks have multiple rows of sharp, serrated teeth that are constantly replaced as they wear out. Their teeth are designed for capturing and tearing prey, while human teeth are designed for cutting, tearing, and grinding food.
6. Eyes: Sharks have eyes that are well-adapted for vision in low light conditions. They have a reflective layer called the tapetum lucidum behind the retina, which helps to enhance their night vision. Human eyes have a more complex structure and are better suited for color vision and perceiving detail.
7. Size: Sharks can vary greatly in size, with some species reaching lengths of over 40 feet, while humans typically stand around 5-6 feet tall.
These differences in body structure and features reflect the different environments and lifestyles of sharks and humans, and highlight their unique adaptations to their respective habitats and ecological niches.