ZoologyLesson 3 of 4 in the course Diversity of Animals

Mollusk and Annelid Body Plans, Classes, and Adaptations

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Mollusks are a highly diverse animal group, ranging from shell-bearing grazers to intelligent predators such as octopuses. This lesson introduces the shared features that help identify mollusks and explains how their bodies support different ways of life.

The phylum Mollusca includes more than 75,000 described species, with some summaries estimating about 85,000. Mollusks are especially prominent in marine environments: an estimated 23 percent of known marine species belong to this phylum. Their body forms vary widely, but many share a basic set of anatomical features.

All flashcards

What is metamerism in annelids?
The organization of the body into repeated segments, with many features repeated from segment to segment.
What are parapodia, and what do they do?
Paired, unjointed appendages on polychaete segments that assist with locomotion and breathing.
What does the clitellum do in oligochaetes?
It secretes mucus that binds mating individuals and later forms a protective egg cocoon.
How many hearts do squid and octopuses have, and what do they do?
They have two hearts that move blood through the gills and a systemic heart that pumps blood through the body.
What is the mantle cavity?
A space beneath the mantle that can contain gills and serve other functions.

Quiz questions

  1. How do bivalves typically obtain food?Answer: They filter particles from water.
  2. How does a cephalopod produce jet propulsion?Answer: It expels water from the mantle cavity through its funnel.
  3. Where does gas exchange occur in annelids?Answer: Across the moist body surface.
  4. Which combination of traits is characteristic of leeches?Answer: Anterior and posterior suckers, with no chaetae.
  5. What is characteristic of branchiobdellids?Answer: They are obligate symbionts, mainly associated with freshwater crayfish.

Based on Concepts of Biology by Samantha Fowler, Rebecca Roush, James Wise (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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