Table of contents

1. Introduction to Biology2h 42m
2. Chemistry3h 37m
3. Water1h 26m
4. Biomolecules2h 23m
5. Cell Components2h 26m
6. The Membrane2h 31m
7. Energy and Metabolism2h 0m
8. Respiration2h 40m
9. Photosynthesis2h 49m
10. Cell Signaling59m
11. Cell Division2h 47m
12. Meiosis2h 0m
13. Mendelian Genetics4h 44m
14. DNA Synthesis2h 27m
15. Gene Expression3h 6m
16. Regulation of Expression3h 31m
17. Viruses37m
- Viruses
  37m
18. Biotechnology2h 58m
19. Genomics17m
- Genomes
  17m
20. Development1h 5m
21. Evolution3h 1m
22. Evolution of Populations3h 53m
23. Speciation1h 37m
24. History of Life on Earth2h 6m
25. Phylogeny2h 31m
26. Prokaryotes4h 59m
27. Protists1h 12m
28. Plants1h 22m
29. Fungi36m
- Fungi
  19m
- Fungi Reproduction
  17m
30. Overview of Animals34m
- Overview of Animals
  34m
31. Invertebrates1h 2m
32. Vertebrates50m
33. Plant Anatomy1h 3m
34. Vascular Plant Transport1h 2m
- Water Potential
  1h 2m
35. Soil37m
- Soil and Nutrients
  20m
- Nitrogen Fixation
  16m
36. Plant Reproduction47m
- Flowers
  33m
- Seeds
  14m
37. Plant Sensation and Response1h 9m
38. Animal Form and Function1h 19m
39. Digestive System1h 10m
- Digestion
  1h 3m
- Blood Sugar Homeostasis
  7m
40. Circulatory System1h 49m
41. Immune System1h 12m
42. Osmoregulation and Excretion50m
- Osmoregulation and Excretion
  50m
43. Endocrine System1h 4m
- Endocrine System
  1h 4m
44. Animal Reproduction1h 2m
- Animal Reproduction
  1h 2m
45. Nervous System1h 55m
- Neurons and Action Potentials
  1h 8m
- Central and Peripheral Nervous System
  46m
46. Sensory Systems46m
- Sensory System
  46m
47. Muscle Systems23m
- Musculoskeletal System
  23m
48. Ecology3h 11m
49. Animal Behavior28m
- Animal Behavior
  28m
50. Population Ecology3h 41m
51. Community Ecology2h 46m
52. Ecosystems2h 36m
53. Conservation Biology24m
- Conservation Biology
  24m

30. Overview of Animals

Overview of Animals

General Biology

30. Overview of Animals

Overview of Animals

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1:26 minutes

Textbook Question

Name two phyla of animals that are radially symmetric and two that are bilaterally symmetric. How do the general lifestyles of radial and bilateral animals differ?

Verified step by step guidance

Identify the phyla of animals that exhibit radial symmetry. Radial symmetry means that the body plan of the organism can be divided into similar halves by passing a plane at any angle along a central axis. Common examples of radially symmetric animals are found in the phyla Cnidaria (which includes jellyfish and corals) and Echinodermata (which includes starfish and sea urchins).

Identify the phyla of animals that exhibit bilateral symmetry. Bilateral symmetry means that the body plan can only be divided into mirror-image halves along one particular plane. This type of symmetry is seen in phyla such as Chordata (which includes all vertebrates like fish, birds, mammals) and Arthropoda (which includes insects, spiders, and crustaceans).

Explain the general lifestyle of radially symmetric animals. These animals typically have a sessile or planktonic lifestyle, meaning they either remain fixed in one place or drift in water currents. Their radial symmetry is advantageous for these lifestyles as it allows them to interact with the environment from all sides equally.

Discuss the general lifestyle of bilaterally symmetric animals. These animals are usually more active and mobile compared to radially symmetric animals. The bilateral body plan facilitates directional movement and is often associated with a more complex nervous system and sensory organs concentrated at the front end, aiding in coordinated movement and environmental interaction.

Summarize the differences in lifestyle between radially and bilaterally symmetric animals. Radially symmetric animals are generally less mobile and interact with their environment in a more passive way, while bilaterally symmetric animals tend to have active lifestyles with enhanced mobility and sensory capabilities.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Radial Symmetry

Radial symmetry is a body plan in which the body can be divided into similar halves by multiple planes passing through a central axis. This symmetry is commonly found in organisms like jellyfish and sea anemones, allowing them to interact with their environment from all directions. Radially symmetric animals typically have a more sessile or free-floating lifestyle, as their body structure supports a lifestyle that does not require directional movement.

Bilateral Symmetry

Bilateral symmetry refers to a body plan where the organism can be divided into two identical halves along a single plane, usually resulting in a distinct head and tail (anterior and posterior) and a top and bottom (dorsal and ventral). This symmetry is characteristic of animals such as humans and insects, facilitating directional movement and complex behaviors. Bilaterally symmetric animals often exhibit more active lifestyles, allowing for efficient locomotion and interaction with their environment.

Lifestyle Differences

The general lifestyles of radially and bilaterally symmetric animals differ primarily in their movement and feeding strategies. Radial animals tend to be more passive, often relying on currents for movement and having a diet that consists of small particles or prey that come into contact with their bodies. In contrast, bilateral animals are typically more active hunters or foragers, using their streamlined bodies to navigate their environment efficiently and pursue prey.

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