Vertebrates: Characteristics and Classification

• Vertebrates are part of the Phylum Cordata.
• Vertebrates have a dorsal nerve cord.
• The phylum cordata include Urochordates, Cephalochordates, Fish, Amphibians, Reptiles, Birds, and Mammals.

Characteristics of Vertebrates

• Vertebrates possess a spinal cord, also known as médula espinal.
• Vertebrates have an internal skeleton.
• Vertebrates' nervous system has nerves and a central nervous system comprising the brain and spinal cord.
• Vertebrates have highly developed sense organs.
• Vertebrates have a closed circulatory system.
• They reproduce through sexual reproduction.
• Fish, birds, and amphibians are oviparous, laying eggs.
• Mammals are viviparous, with the embryo developing inside the mother.
• Some reptiles exhibit viviparity.
• Ovoviviparous animals produce eggs that develop and hatch inside the mother's body, giving birth to live young; some snakes and sharks do this.

Fish

• Aquatic vertebrates are ectothermic.
• Almost all fish are covered in scales.
• Almost all fish have fins.
• Many fish possess a swim bladder, an internal sac filled with gas for buoyancy control.
• A lateral line is a sense organ along the fish's body that detects movement.

Cartilaginous Fish

• Cartilaginous fish have cartilaginous skeletons.
• These fish lack a swim bladder.
• Their skin is covered with tooth-like scales.
• The mouth is in a ventral position.
• They use internal fertilization.
• Cartilaginous fish can be oviparous, viviparous, or ovoviviparous

Bony Fish

• Bony fish possess a bony skeleton.
• Bony fish have gills protected by an operculum.
• Bony fish use external fertilization.
• They are oviparous.

Amphibians

• Amphibians are ectothermic vertebrates with bare, moist skin.
• Amphibians depend on bodies of water.
• Amphibian eggs lack an amniotic membrane, so they must be laid in water.
• Larvae breathe through gills, while adults possess rudimentary lungs and depend on cutaneous respiration through moist skin.
• Amphibians use sexual reproduction with external fertilization and undergo metamorphosis.
• They hibernate during the winter, reducing activity.

Reptiles

• Reptiles are ectothermic vertebrates.
• Reptiles have skin covered with hard scales to prevent drying.
• Reptiles have lungs and utilize sexual reproduction with internal fertilization
• Reptiles lay amniotic eggs.

Explore the characteristics of vertebrates, including their spinal cord and internal skeleton. Learn about the phylum Cordata and the different classes of vertebrates, such as fish, amphibians, reptiles, birds, and mammals. Discover their diverse reproductive strategies.