Overview of Animal Biology

Study of animal life, including structure, function, growth, evolution, and interactions with the environment.
Sub-disciplines include zoology, ecology, ethology, and comparative anatomy.

Homeostasis: Maintaining stable internal conditions despite external changes.
Respiration: Oxygen intake and carbon dioxide expulsion; methods include gills (in fish) and lungs (in mammals).
Circulatory System: Transports nutrients, gases, and waste; can be open (e.g., arthropods) or closed (e.g., mammals).
Nervous System: Coordinates responses to stimuli; includes central (brain and spinal cord) and peripheral systems.

Asexual Reproduction: Involves a single parent; methods include budding and fission.
Sexual Reproduction: Involves two parents; leads to genetic diversity.
- Fertilization can be internal (e.g., mammals) or external (e.g., fish).

Embryonic Development: Stages include zygote, blastula, and gastrula.
Metamorphosis: Transformation from larval to adult stages in some species (e.g., frogs).

Natural Selection: Process by which traits that enhance survival and reproduction become more common.
Speciation: Formation of new species due to evolutionary processes.
Adaptations: Traits that enhance survival in specific environments (e.g., camouflage, mimicry).

Habitats: The natural environment where an organism lives.
Ecosystems: Communities of living organisms interacting with their physical environment.
Food Chains and Webs: Illustrate energy transfer through trophic levels:
- Producers (plants)
- Consumers (herbivores, carnivores, omnivores)
- Decomposers (fungi, bacteria)

Focus on protecting species and their habitats.
Importance of biodiversity for ecosystem health and resilience.
Threats include habitat destruction, pollution, climate change, and invasive species.

Animal research plays a crucial role in understanding biology and medicine.
Ethical considerations include animal welfare and the justification of research benefits.

Animal biology examines the structure, function, growth, evolution, and environmental interactions of animals.
Key sub-disciplines include zoology (study of animals), ecology (relations between organisms and their environment), ethology (animal behavior), and comparative anatomy (similarities and differences in anatomy across species).

Animals are categorized into groups based on defining characteristics.
Invertebrates: Do not possess a backbone; examples comprise insects, arachnids, and mollusks.
Vertebrates: Have a backbone, divided into five major classes:
- Mammals: Warm-blooded, have fur/hair, and nurse young with milk.
- Birds: Have feathers, lay eggs, and are warm-blooded.
- Reptiles: Cold-blooded, with scales; generally lay eggs and include snakes and lizards.
- Amphibians: Begin life in water (with gills) and transition to land as adults (with lungs).
- Fish: Aquatic, gills for respiration, and scales covering their bodies.

Homeostasis: Ability to maintain stable internal conditions (e.g., temperature, pH).
Respiration: Process of gas exchange; gills in fish and lungs in mammals facilitate oxygen uptake and carbon dioxide removal.
Circulatory System: Can be open (e.g., arthropods with hemolymph) or closed (e.g., mammals with blood), transporting nutrients, gases, and waste.
Nervous System: Consists of the central nervous system (brain and spinal cord) and peripheral nervous system; coordinates responses to environmental stimuli.

Asexual Reproduction: Involves a single parent, using methods such as budding (e.g., hydra) and fission (e.g., flatworms).
Sexual Reproduction: Involves two parents, resulting in increased genetic variation.
Fertilization can occur internally (e.g., in mammals) or externally (e.g., in many fish species).

Embryonic Development: Progresses through key stages: zygote (fertilized egg), blastula (hollow sphere of cells), gastrula (three germ layers form).
Metamorphosis: A developmental change where organisms transform from larval forms to adults, seen in species such as frogs.

Natural Selection: Mechanism driving evolution; advantageous traits are preserved and become more common.
Speciation: The evolutionary process leading to the formation of new species.
Adaptations: Traits that improve an organism's ability to survive in its environment, examples include camouflage and mimicry.

Habitats: Specific natural environments where organisms reside.
Ecosystems: Interacting communities of organisms along with their physical surroundings.
Food Chains and Webs: Visualize energy transfer through different trophic levels, including:
- Producers (plants that synthesize their food through photosynthesis)
- Consumers (species that eat plants or other animals)
- Decomposers (organisms such as fungi and bacteria that break down dead organic material).

Aims to protect species and their natural habitats.
Emphasizes the crucial role of biodiversity in maintaining ecosystem health and resilience.
Major threats to biodiversity include habitat destruction, pollution, climate change, and the introduction of invasive species.

Animal research is essential for advancing biological knowledge and medical discoveries.
Ethical considerations revolve around the welfare of research animals and whether the benefits of the research justify potential harm.