Vertebrate Animal Groups and Features

Vertebrata

Vertebrates are characterized by a backbone created from small parts called vertebrae and an endoskeleton. The endoskeleton can be made of:

• Cartilage (Cyclostomata, Chondrichthyes)
• Bones (Osteichthyes, Amphibians, Reptiles)

Key systems include:

• Central Nervous System: Brain, spinal cord, peripheral nerves forming a tubular nervous system.
• Vascular System: Closed, chambered heart.
• Breathing System: Gills, lungs.
• Excretory System: Kidneys.

They mostly have four limbs, although these are sometimes modified (e.g., fish fins, bird wings) or absent (e.g., snakes).

Cyclostomata (Jawless Fish)

These animals lived on Earth 500 million years ago. They live in shallow seas, mild climatic areas, and sometimes in fresh water. Their mouth opening is round; they lack jaws but have a mouth with teeth. They do not have a true skeleton, only a cartilaginous notochord.

They feed on fish and other marine organisms, eating tissues and sucking blood. They breathe by gills and produce slime. They lack a tail fin and fin edge. They look like eels, cannot see well but have a good sense of smell.

Divided into:

• Cephalaspidomorphi (Lampreys)
• Pteraspidomorphi (Hagfish)

Chondrichthyes (Cartilaginous Fish)

Orders:

• Lamniformes (Ground Sharks)
• Rajiformes (Skates and Rays)
• Holocephali (Chimaeras)

They are mostly predators, though some are filter feeders. They regenerate their teeth and have very developed sense organs:

• Very good sight (up to 100m in dark water)
• Very good smell (10,000 times better than humans); smell pits are on the upper part of the head.
• Highly developed taste.
• Excellent hearing up to several kilometers.
• Lateral line (bočná čiara) with sensitive cells in a jelly-like matter, sensitive to vibrations.
• Ampullae of Lorenzini, a special organ on their head for perceiving electrical fields around other organisms.
• Sense of touch.

Reproduction: Internal fertilization. Ventral fins are modified into a copulatory organ. They are oviparous (egg-laying), but some are ovoviviparous (eggs hatch inside the mother).

Representatives: Blue Shark, Whale Shark, Basking Shark, Hammerhead Shark.

Rajiformes (Skates and Rays)

They live in the sea, often at the bottom, though some are found in fresh water or swim higher (e.g., Manta rays). They have a flat body with large pectoral fins fused to the head and body. Eyes and breathing openings are on the dorsal side, while the mouth, visceral clefts, and smell pits are on the ventral side. They have a long tail, sometimes with a sharp spike containing poisonous glands for hunting. Some species have muscles that produce electricity (e.g., Electric Rays).

Representatives: Sawfish, Thorny Skate, Electric Ray, Manta Ray.

Osteichthyes (Bony Fish)

Bony fish live in marine or fresh water. They have a bony skeleton consisting of:

• Skull
• Backbone
• Fins

Their body is covered by scales and slime for protection and gliding in water. They have odd and paired fins:

• Paired: Pectoral (hrudné), Ventral (brušné)
• Odd: Dorsal fin, Tail fin, Anal fin

They have well-developed senses: sight, smell, touch, hearing, taste, and a lateral line.