Podcast
Questions and Answers
What is a key innovation in animal evolution?
What is a key innovation in animal evolution?
What is a characteristic shared by all animals?
What is a characteristic shared by all animals?
What is a characteristic of radial symmetry?
What is a characteristic of radial symmetry?
What is a type of symmetry exhibited by members of the phylum Cnidaria?
What is a type of symmetry exhibited by members of the phylum Cnidaria?
Signup and view all the answers
What is the primary mode of energy and organic molecule acquisition in animals?
What is the primary mode of energy and organic molecule acquisition in animals?
Signup and view all the answers
What is an advantage of bilateral symmetry?
What is an advantage of bilateral symmetry?
Signup and view all the answers
Which characteristic distinguishes animals from autotrophic plants and algae?
Which characteristic distinguishes animals from autotrophic plants and algae?
Signup and view all the answers
What is the term for animals that are incapable of moving from place to place?
What is the term for animals that are incapable of moving from place to place?
Signup and view all the answers
What is the product of the first stage of embryonic development in animals?
What is the product of the first stage of embryonic development in animals?
Signup and view all the answers
Which of the following is a unique characteristic of animals?
Which of the following is a unique characteristic of animals?
Signup and view all the answers
Study Notes
Key Characteristics of Animals
- All animals are heterotrophs, obtaining energy and organic molecules by consuming other organisms.
- All animals are multicellular, with many having complex bodies.
- Animals lack rigid cell walls, and their cells are held together by extracellular frames of structural proteins like collagen.
Features of Animal Movement
- Animals move more rapidly and in more complex ways, related to the flexibility of their cells and the evolution of nerve and muscle tissues.
- Not all animals can move from place to place; some are sessile or sedentary.
Diversity of Form and Habitat
- Animals vary greatly in form, ranging in size from microscopic to enormous.
- Almost all animals lack a backbone and are therefore called invertebrates.
- Animals are grouped into 35-40 phyla, with most occurring in the sea, but many also in fresh water and on land.
Reproduction and Development
- Most animals reproduce sexually, with non-mobile eggs being much larger than small, usually flagellated sperm.
- Embryonic development begins with a series of mitotic divisions producing a ball of cells (the blastula).
Tissues and Body Structure
- Cells of most animals are organized into structural and functional units called tissues.
- Development from a zygote begins with a series of divisions, called cleavage, which produces a multicellular structure called a blastula.
Evolution of the Animal Body Plan
- Five key innovations in animal evolution: symmetry, tissues, body cavity, patterns of development, and segmentation.
Symmetry in Animals
- Virtually all animals have a symmetry defined along an imaginary axis drawn through the animal's body (exception: sponges).
- There are two main types of symmetry: radial and bilateral.
Radial Symmetry
- Exhibited by members of the phylum Cnidaria (jellyfish, sea anemones, and corals).
- Body parts are arranged around a central axis.
- Can be divided into two equal halves by any plane that passes through the center.
Bilateral Symmetry
- Body has right and left halves that are mirror images.
- Only the sagittal plane divides the animal into two equal halves (left and right).
- Has dorsal and ventral portions divided by the frontal plane, and anterior and posterior portions divided by the transverse plane.
Advantages of Bilateral Symmetry
- Advantages not specified in the text.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
This quiz covers the fundamental characteristics of animals, including heterotrophy and multicellularity. Learn about how animals obtain energy and organic molecules, and their complex body structures.
