Key Characteristics of Vertebrate Animal Groups

Main Characteristics of Vertebrate Animals

Vertebrate animals belong to the Animal Kingdom and possess the following characteristics:

• They have an internal skeleton that allows movement, protects the organs, and gives support to their body.
• They have blood to carry nutrients and waste products throughout the body.
• They have articulated limbs (fins, wings, or legs).

We are going to study the following vertebrate groups:

Classification and Features of Fish

• Aquatic: They have a fusiform body (thinner at the tips) and fins. They breathe through gills.
• Poikilothermic: They cannot maintain a constant body temperature.
• Lateral line: A line crossing their body that is able to detect vibrations in the water.
• External fertilization: Gametes join in the environment, outside of the female’s body.
• Reproduction: They can be oviparous (the embryo develops inside an egg outside the mother’s body) or ovoviviparous (the embryo develops inside an egg inside the mother’s body, such as some sharks).

Major Groups of Fish

• Bony fish: These have a bony skeleton and gills protected by an operculum. Examples include trout and salmon.
• Cartilaginous fish: These have a cartilaginous skeleton and visible gills. Examples include sharks and rays.

Distinctive Traits of Birds

• Habitat: Terrestrial or aquatic, but all of them breathe through lungs.
• Homeothermic: They can maintain a constant body temperature.
• Reproduction: Internal fertilization; they are oviparous.
• Physical features: Their body is covered with feathers. Upper limbs are wings. The shape of their beaks depends on the type of feeding, while the shape of their legs depends on their habitat.
• Light body: They have air sacs between the organs and inside the bones to facilitate flight.

Types of Birds

• Flying birds: They have the ability to fly. Examples include eagles and parrots.
• Flightless birds: They cannot fly. Examples include the ostrich, kiwi, and penguins.

Biological Features of Mammals

• Habitat: Terrestrial or aquatic, but all of them breathe through lungs.
• Homeothermic: They maintain a constant body temperature.
• Reproduction: Internal fertilization; they can be oviparous or viviparous.
• Physical features: Their body is covered with fur or hair. They are the only group of vertebrates that have ears (except for whales, dolphins, manatees, and seals).
• Mammary glands: They possess glands that produce milk, which the newborns feed upon.

The Three Groups of Mammals

• Monotremes: These are oviparous. Examples include platypuses and echidnas.
• Marsupials: These are viviparous, but their babies finish their development inside an external pouch called a marsupium. Examples include the koala and kangaroo.
• Placentals: These are viviparous with a placenta. Examples include tigers and elephants.