Animal Anatomy and Ecology Overview

Definition: The study of the structure and organization of animals.
Levels of Organization:
- Cellular: Basic unit is the cell.
- Tissue: Groups of similar cells performing a function (e.g., epithelial, connective, muscular, and nervous tissues).
- Organ: Structures composed of different tissues (e.g., heart, lungs, liver).
- System: Groups of organs working together (e.g., circulatory, respiratory, digestive systems).
Common Anatomical Features:
- Symmetry: Bilateral (two-sided), radial (around a central axis), asymmetrical.
- Body Cavity: Coelomates (true body cavity), pseudocoelomates (false body cavity), acoelomates (no body cavity).
- Skeleton: Types include hydrostatic, exoskeleton, and endoskeleton.

Definition: The study of interactions between organisms and their environment.
Key Concepts:
- Ecosystems: Composed of living (biotic) and non-living (abiotic) components.
- Habitat: The natural environment where an organism lives.
- Niche: The role or function of an organism within an ecosystem.
- Homeostasis: The ability of an organism to maintain stable internal conditions despite external changes.
Levels of Ecology:
- Individual: Study of single organisms.
- Population: Study of groups of the same species.
- Community: Interactions between different species.
- Ecosystem: Interactions between communities and their environment.
- Biosphere: Global sum of all ecosystems.
Ecological Relationships:
- Predation: One species hunts another.
- Competition: Species compete for resources.
- Symbiosis: Close interactions between species (mutualism, commensalism, parasitism).

Types:
- Asexual: Involves one parent, offspring are genetically identical (e.g., binary fission, budding, fragmentation).
- Sexual: Involves two parents, offspring are genetically diverse due to genetic recombination.
Processes:
- Fertilization: Fusion of male and female gametes to form a zygote.
- Development: Growth stages from zygote to mature organism, can be direct or involve larval stages.
Reproductive Strategies:
- K-strategy: Fewer offspring with higher parental investment (e.g., mammals).
- r-strategy: Many offspring with less parental investment (e.g., insects).
Hormonal Regulation: Hormones play key roles in the reproductive cycle (e.g., estrogen, testosterone).
Phenomena:
- Mating behavior: Various strategies to attract mates.
- Parental care: Varies greatly between species in terms of investment in offspring.

Definition: The study of the structure of animals, including how their bodies are organized.
Levels of Organization:
- Cellular: The most basic unit of life, cells are the building blocks of all animals.
- Tissue: Groups of similar cells working together to perform a specific function. There are four main tissue types: epithelial, connective, muscular, and nervous.
- Organ: Structures composed of different tissues that work together to perform a complex function.
- System: A group of organs that work together as a coordinated unit.
Common Anatomical Features:
- Symmetry: Describes the balance of an animal's body.
  - Bilateral: Two symmetrical sides (example: humans).
  - Radial: Symmetry around a central axis (example: starfish).
  - Asymmetrical: No symmetry (example: sponges).
- Body Cavity: The space within an animal's body, can be:
  - Coelomate: True body cavity lined with mesoderm.
  - Pseudocoelomate: False body cavity not fully lined with mesoderm.
  - Acoelomate: No body cavity.
- Skeleton: Provides support and structure.
  - Hydrostatic: Fluid-filled cavity that provides support (example: earthworms).
  - Exoskeleton: External, hard covering (example: insects).
  - Endoskeleton: Internal skeleton (example: mammals).

Definition: The study of how organisms interact with their environment.
Key Concepts:
- Ecosystem: A community of living organisms (biotic) and their non-living surroundings (abiotic) interacting as a unit.
- Habitat: The natural environment where an organism lives.
- Niche: An organism's role or function within an ecosystem, including its food source, habitat, and interactions with other species.
- Homeostasis: The ability of an organism to maintain a stable internal environment despite external changes.
Levels of Ecology:
- Individual: Studying a single organism.
- Population: Studying a group of organisms of the same species.
- Community: Studying interactions between different species in the same area.
- Ecosystem: Studying interactions between communities and their environment.
- Biosphere: The global sum of all ecosystems, encompassing all life on Earth.
Ecological Relationships:
- Predation: One species (predator) hunts and consumes another (prey).
- Competition: Organisms compete for resources like food, water, or space.
- Symbiosis: Close interactions between species:
  - Mutualism: Both species benefit.
  - Commensalism: One species benefits, the other is unaffected.
  - Parasitism: One species benefits, the other is harmed.

Types:
- Asexual: Reproduction involving one parent, producing genetically identical offspring. Examples:
  - Binary fission: Single-celled organisms splitting into two.
  - Budding: Offspring growing from the parent's body.
  - Fragmentation: Parts of the parent breaking off and developing into new individuals.
- Sexual: Reproduction involving two parents, producing genetically diverse offspring.
Processes:
- Fertilization: The fusion of male and female gametes (sex cells) to form a zygote.
- Development: The process of growth and development from zygote to a mature organism.
  - Direct development: Young resemble adults (e.g., humans).
  - Indirect development: Young undergo larval stages (e.g., butterflies).
Reproductive Strategies:
- K-strategy: Fewer offspring with higher parental investment. Examples: Mammals.
- r-strategy: Many offspring with less parental investment. Examples: Insects.
Hormonal Regulation: Hormones play crucial roles in the reproductive cycle.
- Estrogen: Female sex hormone important for development and reproduction.
- Testosterone: Male sex hormone important for development and reproduction.
Phenomena:
- Mating behavior: Diverse strategies used by animals to attract mates.
- Parental care: The level of care provided by parents to offspring varies greatly and is a major factor in reproductive success.