Animal

Definition

An animal is a living organism that is capable of independent movement, possesses specialized sensory organs, and typically derives energy from the consumption of organic material. Animals are multicellular eukaryotes that belong to the kingdom Animalia, distinguished from plants, fungi, and other forms of life.

5 Must Know Facts For Your Next Test

1. Animals are heterotrophic, meaning they obtain energy by consuming other organisms, either plants or other animals.
2. The vast majority of animals are multicellular, with specialized cells that perform different functions within the organism.
3. Animals exhibit a wide range of behaviors, including feeding, reproduction, and social interactions, which are often complex and highly adaptable.
4. The study of animal behavior, known as ethology, is an important field in biology that helps us understand the evolution and ecology of different species.
5. Animals play crucial roles in various ecosystems, serving as producers, consumers, and decomposers, and contributing to the cycling of nutrients and energy within those systems.

Review Questions

• Explain how the concept of hierarchical inheritance relates to the classification of animals.
  • Hierarchical inheritance in the context of animal classification refers to the taxonomic system that groups organisms based on their shared characteristics and evolutionary relationships. This hierarchical system starts with the broadest category, the kingdom Animalia, and progressively narrows down to more specific classifications, such as phyla, classes, orders, families, genera, and species. Each level of the hierarchy reflects the degree of similarity and evolutionary relatedness between the organisms, with those at higher levels sharing more fundamental characteristics and those at lower levels exhibiting more specialized traits.
• Describe how the diverse behaviors and adaptations of animals are shaped by their evolutionary history and environmental pressures.
  • The wide range of behaviors and adaptations observed in animals are the result of their evolutionary history and the selective pressures of their environment. Through the process of natural selection, animals have developed specialized traits and behaviors that enhance their chances of survival and reproduction within their particular ecological niche. For example, predatory animals may exhibit complex hunting strategies, while prey species may have evolved effective defense mechanisms or camouflage. Similarly, animals living in different climates or habitats have adapted their physiology, morphology, and behaviors to best suit the demands of their environment, such as the development of insulation in Arctic species or the ability to conserve water in desert-dwelling organisms.
• Analyze how the classification of animals into vertebrates and invertebrates reflects fundamental differences in their anatomical structures and evolutionary lineages.
  • The distinction between vertebrates and invertebrates is a crucial aspect of animal classification that highlights significant differences in their anatomical structures and evolutionary histories. Vertebrates, such as mammals, birds, reptiles, amphibians, and fish, are characterized by the presence of a backbone or spinal column, which provides structural support and protection for the central nervous system. In contrast, invertebrates, which include insects, spiders, crabs, and many other organisms, lack a true backbone and instead have a variety of alternative support structures, such as exoskeletons or hydrostatic skeletons. These fundamental differences in body plan and internal anatomy reflect the divergent evolutionary paths taken by these two broad groups of animals, with vertebrates and invertebrates representing distinct branches on the tree of life that have adapted to a wide range of ecological niches.

Related terms

Vertebrate: A vertebrate is an animal that has a backbone or spinal column, including mammals, birds, reptiles, amphibians, and fish.

Invertebrate: An invertebrate is an animal that does not have a backbone or spinal column, such as insects, spiders, crabs, and jellyfish.

Taxonomy: Taxonomy is the science of classifying organisms into a hierarchical system based on their physical characteristics and evolutionary relationships.