Invertebrate Phyla: Flatworms, Annelids, and Molluscs

This collection of flashcards covers key facts and concepts regarding flatworms, annelids, and molluscs as discussed in your lecture notes.

What phylum do flatworms belong to?

Phylum Platyhelminthes.

What type of symmetry do flatworms exhibit?

Bilateral symmetry.

Do flatworms have one or two openings to their digestive tract?

Flatworms have one opening that serves as both mouth and anus.

What is the body plan of flatworms characterized by?

Three tissue layers: ectoderm, mesoderm, and endoderm.

How do flatworms primarily reproduce?

Flatworms reproduce both sexually and asexually.

What is a unique regenerative ability of some flatworms?

Some flatworms can regenerate lost body parts.

What is the method of feeding in flatworms?

Flatworms use a muscular pharynx to eat, functioning as both mouth and anus.

Can flatworms be parasitic?

Yes, some flatworms are parasitic.

What are tapeworms?

Parasites with long pseudo-segmented bodies that do not require a digestive system.

What characterizes annelids?

Soft-bodied with many repeating segments.

What is segmentation in annelids?

Repetition of identical units that can serve different purposes.

How do annelids circulate nutrients?

Annelids have a circulatory system with hearts and arteries.

What type of fertilization do most annelids perform?

External fertilization.

What is a key characteristic of earthworms?

They are important soil decomposers.

What do leeches contribute to medical treatments?

Leeches help prevent tissue death in certain surgical cases.

What unusual feeding structure do some molluscs have?

The radula, a scraping tongue-like organ.

What is the mantle in molluscs?

The mantle protects organs and secretes shells.

What is unique about bivalves?

They have two hinged shells and are filter feeders.

How do octopi typically hunt?

Using their tentacles.

What is a common habitat for snails and slugs?

They can inhabit marine, terrestrial, and freshwater environments.

What defines the diet of molluscs?

They have a huge variety of diets from herbivorous to carnivorous.

What do molluscs use for movement?

The ventral muscular foot.

What role do molluscs play in human economy?

Molluscs are important food sources and contribute to beach formation.

What type of organism has a branched gastrovascular cavity?

Some flatworms have a branched gastrovascular cavity.

What is the significance of planaria in ecosystems?

They often act as decomposers.

In what environment do polychaetes primarily live?

Marine or aquatic environments.

What is a unique feature of leeches?

Leeches have suckers on either end of their body.

What do liver flukes typically feed on?

They are parasites that feed on host blood.

How do snails adapt if they lose their shells?

Some lose their shells after the larval stage.

Do all molluscs have a radula?

No, bivalves lack a radula.

What is the main reproductive strategy of most molluscs?

Most reproduce sexually.

What is the physical trait of annelids widely observed?

Segmented body.

What do you call the structure that supplies nutrition in flatworms?

Digestive tract.

What is an example of a free-living flatworm?

Planaria.

How does the body of a tapeworm differ from other worms?

Tapeworms are long and pseudo-segmented.

What are the common segments in annelids called?

Metameres.

What are the feeding habits of earthworms?

Earthworms are soil decomposers.

What type of circulatory system do molluscs possess?

Basic circulatory system with a heart.

Why are molluscs considered important economically?

They provide food and materials for various industries.

What are some adaptations of octopi?

They have well-developed brains and sensory organs.

How do flatworms primarily maximize efficiency in feeding?

They partition time between eating and waste expulsion.

How many tissue layers do annelids have?

Three tissue layers.

What is a method of survival for leeches?

They can be parasites.

What is the term for organisms like clams that filter feed?

Filter feeders.

What distinguishes terrestrial annelids from others?

Their ability to live in soil.

How do octopus use their propulsion for movement?

They expel water to move quickly.

What is bilaterally symmetrical?

Organisms that can be divided into mirror-image halves.

What is a significant role of polychaetes in their environments?

They help maintain ecological balance by being predators.

What adaptations do bivalves lack that other molluscs have?

Bivalves lack a radula.

In which part of the mollusc’s body are the internal organs typically located?

In the mantle.