Vertebrate Animals and Endoskeleton

Vertebrates

• Vertebrate means an animal has a backbone.
• The vertebral column first evolved in fish and is the core of the endoskeleton (internal skeleton), housing and protecting the spinal cord.

Vertebral Column

• In many species, shock-absorbing discs cushion vertebrae.
• The endoskeleton is made up of cartilage or bone.
• Cartilage is a tough tissue that contains a protein called collagen.
• Bone is a hard tissue that consists of a collagen matrix with calcium.
• Bone is less flexible, but cartilage is stronger.

Fish

• Fish are aquatic vertebrates.
• They make up more than half of all vertebrate species.
• Scales protect fish from predators and parasites.

Adaptations for Water

• Gills allow water to enter the mouth, pass over the gills, and exit through an opening, absorbing oxygen.
• Fins are used for swimming.
• A system of muscles is used for movement.
• Swim-bladder is a balloon-like organ that contains gas, allowing fish to float and have buoyancy.

Fish Organ Systems

• Fish have a circulatory system with a two-chambered heart.
• They have a digestive system with several organs and glands.
• They have a central nervous system with a brain and sensory organs.

Shark Specifics

• Sharks can sense low levels of electricity emitted by their prey.
• Sharks do not have a swim-bladder.
• Sharks do not have bones, only cartilage.
• Sharks have a two-chambered heart.
• Male sharks have claspers on the outside of the body for sperm production.
• Sharks have lots of oil in the body, which is lighter than water, helping them float.