Similarities:
* Aquatic: Both sharks and fish live in water.
* Gills: Both use gills to breathe underwater.
* Vertebrates: Both are vertebrates, meaning they have a backbone.
* Cold-blooded: Both are cold-blooded, meaning their body temperature changes with the surrounding water.
* Streamlined bodies: Both have streamlined bodies that help them move efficiently through the water.
* Fins: Both use fins for stability, balance, and movement.
Differences:
* Skeleton: Sharks have a skeleton made of cartilage (a flexible tissue), while fish have a skeleton made of bone.
* Skin: Sharks have rough, sandpaper-like skin covered in tiny teeth-like scales called denticles, while fish have scales that can be smooth, bony, or spiky.
* Reproduction: Sharks typically give birth to live young, while fish lay eggs.
* Mouth: Sharks have their mouths on the underside of their heads, while most fish have their mouths on the front.
* Teeth: Sharks have rows of replaceable teeth that constantly grow, while fish teeth can be small, sharp, or even absent.
* Body Shape: Sharks come in various shapes, but many have a torpedo-like body. Fish have a wider variety of body shapes, including flat, elongated, and even spherical.
To Summarize:
Sharks and fish share many characteristics as aquatic vertebrates but also have some significant differences, most notably in their skeletons, skin, reproduction, and mouth/teeth structure.