Subphylum Invertebratae

Body Symmetry

Jellyfish (radial), Lobster (bilateral), Sponge (asymmetrical)

Animals, whether big or small, complex or simple, with or without a backbone, all share common characteristics. All animals are multicellular heterotrophic eukaryotes with the ability to move at some point in their lives. Invertebrates are animals that have no backbone. When classifying invertebrates, scientists characterize different organisms based on body symmetry. Symmetry is the distribution of duplicate body parts and shapes within the body of an organism. There are three types of body symmetry exhibited by invertebrates.

• Animals with radial symmetry have no right or left sides, only a top or bottom. Animals like a jellyfish or corals have radial symmetry.
• The majority of animals are bilaterally symmetrical. In these organisms, a line of symmetry divides the body into left and right sides along with a head and tail in addition to a top and bottom.
• Only sponges lack symmetrical body plans and are classified as asymmetrical.
  

Invertebrates

Invertebrates come in all different sizes, from tiny insects to the giant squid, which is the largest invertebrate at more than 60 feet long. This group includes 95 percent of the world’s animals, including animals such as the jellyfish, insects, worms, octopus, clams, and sponges, to name a few. In this interactivity, explore the eight phyla that make up the world’s invertebrates. Click the player button to begin.

View a printable version of the interactivity.

 

 

Subphylum Invertebratae Review

Now that you have explored the subphylum invertebratae, review your knowledge. In this non-graded interactivity, drag the descriptions on the right and drop them next to the terms on the left. Click the player button to get started.