Phylum Annelia Mollusca Nematoda and Rotifera

These flashcards cover key concepts from the lecture notes about animal phylogeny and classification.

What is the common ancestor of all animals?

An ancestral protist.

Which phylum includes sponges?

Porifera.

How many species are in the phylum Annelida?

Approximately 16,500 species.

What stage is included in the life cycle of many mollusks?

A ciliated larval stage called a trochophore.

Which two phyla are classified as lophophorates?

Bryozoa and Brachiopoda.

What type of symmetry do Eumetazoa exhibit?

Bilateral symmetry.

What is a key characteristic of Ecdysozoans?

They are covered by a tough coat called a cuticle.

What process do Ecdysozoans undergo to shed their cuticle?

Ecdysis.

What is the defining feature of Rotifera?

They possess an alimentary canal.

What reproductive strategy do some rotifer species use?

Parthenogenesis, producing offspring from unfertilized eggs.

What is the ecological role of Bryozoa?

They are sessile colonial animals that resemble plants and some species are reef builders.

In which class are gastropods classified?

Class Gastropoda.

What is the shell orientation of Brachiopoda?

Dorsal and ventral.

How many major classes of Phylum Mollusca are there?

Five major classes.

What is the body structure of mammals?

Soft-bodied animals, most protected by a hard shell.

What are the three main parts of mollusks?

Muscular foot, visceral mass, and mantle.

Which class of mollusks contains squids and octopuses?

Class Cephalopoda.

What feature distinguishes leeches from other annelids?

They produce hirudin to prevent blood coagulation.

What is the function of the siphon in cephalopods?

To fire a jet of water for movement.

What is a characteristic feature of Polychaeta?

They have parapodia on each body segment.

What is the defining feature of Oligochaeta?

Earthworms that extract nutrients by eating through soil.

How do nematodes differ from annelids?

Nematodes have an alimentary canal but lack a circulatory system.

What is Trichinella spiralis known for?

It is an important parasite that can affect humans.

What structure do Bryozoans use for feeding?

Lophophore.

How do bivalves mainly feed?

Using gills for feeding and gas exchange.

What type of mouth structure do cephalopods possess?

Beak-like jaws.

What organism is known to be a hermaphrodite among mollusks?

Many snails.

What are the two halves of a clam's shell drawn together by?

Adductor muscles.

What makes gastropods unique in movement?

They move slowly by rippling motions of the foot.

What is a distinctive feature of the class Scaphopoda?

They possess tusk or tooth-shaped shells.

What do nematodes lack that annelids possess?

A circulatory system.

What are the primary habitats of annelids?

Freshwater, marine, and terrestrial environments.

What is the defining trait of the phylum Cnidaria?

Radial symmetry and specialized stinging cells.

What family of mollusks includes clams and oysters?

Class Bivalvia.

How do annelids reproduce?

Earthworms can cross-fertilize and some can reproduce asexually by fragmentation.

What is the purpose of the radula in mollusks?

It is used for feeding by scraping food.

Which animal group has a unique water vascular system?

Echinodermata.

What characteristic do arthropods possess?

Segmented bodies with jointed appendages.

Which animal phylum has the highest number of species?

Ecdysozoans.

What is the main diet of cephalopods?

Carnivores.

What is the significance of the lophophore in feeding?

It traps food particles in ciliated tentacles.

What class do snails belong to?

Class Gastropoda.

What anatomical structure is associated with the reproductive system of earthworms?

Clitellum.

What important role do annelids play in the ecosystem?

Soil aeration and nutrient cycling.

What are the two groups found within the phylum Chordata?

Lancelets and tunicates.

What type of animal are bryozoans often referred to as?

Moss animals.

What do mollusks typically have for protection?

A hard shell made of calcium carbonate.

What type of mouth do rotifers have?

A mouth with jaws called trophi.

Which class of mollusks has multiple calcareous plates?

Class Polyplacophora (chitons).