Animal Diversity and Classification

These flashcards cover the key vocabulary and concepts related to animal diversity and classification, including phyla, characteristics, and developmental processes.

Eukaryotes

Organisms whose cells have a nucleus enclosed within membranes.

Choanoflagellates

Single-celled organisms considered the closest living relatives to animals.

Multicellular

Organisms composed of multiple cells.

Heterotrophic

Organisms that obtain their food by consuming other organisms.

Ingestion

The process of taking in food through the mouth.

Tissues

Groups of cells that have a similar structure and function.

Cleavage

The process of mitotic cell division without growth of the cell ball.

Blastocoel

A hollow ball of cells formed during early embryonic development.

Gastrulation

A phase during embryo development that leads to the formation of germ layers.

Blastula

An early stage of embryonic development consisting of a hollow sphere of cells.

Ectoderm

The outermost germ layer that develops into the skin and nervous system.

Endoderm

The innermost germ layer that develops into the lining of the digestive tract.

Mesoderm

The middle germ layer that develops into muscles, circulatory system, and some organs.

Radial symmetry

Body symmetry in which similar body parts are arranged around a central axis.

Bilateral symmetry

Body symmetry in which there are distinct left and right halves.

Coelom

A fluid-filled body cavity that separates the digestive tract from the outer body wall.

Protostomes

Animal group in which the blastopore develops into the mouth.

Deuterostomes

Animal group in which the blastopore develops into the anus.

Porifera

Phylum that includes sponges, characterized by lack of true tissues.

Cnidaria

Phylum that includes jellyfish, corals, and anemones, known for radial symmetry.

Lophotrochozoa

Superphylum that includes animals like worms and mollusks.

Platyhelminthes

Phylum of flatworms, known for being acoelomate.

Annelida

Phylum of segmented worms with a true coelom.

Mollusca

Phylum that includes snails, clams, and octopuses, with diverse body plans.

Ecdysozoa

Superphylum of animals that molt their exoskeletons.

Nematoda

Phylum that includes roundworms, characterized by a complete digestive system.

Arthropoda

Largest phylum of animals which includes insects, arachnids, and crustaceans.

Echinodermata

Phylum that includes sea stars and urchins, exhibiting radial symmetry as adults.

Chordata

Phylum that includes lancelets, tunicates, and vertebrates.

Triploblasts

Animals with three germ layers: ectoderm, mesoderm, and endoderm.

Cephalization

The concentration of sensory organs at the front end of the organism.

Incomplete digestive system

Digestive system with a single opening for both food intake and waste elimination.

Gastrovascular cavity

Central cavity that serves as both a mouth and an interior digestive system.

Cnidocyte

Specialized cell in Cnidarians that contains a nematocyst.

Nematocyst

An organelle within a cnidocyte that can inject venom.

Lophophore

Ciliated feeding structure found in some aquatic invertebrates.

Trochophore

A larval form of certain aquatic invertebrates characterized by a band of cilia.

Acoelomate

Animals that lack a true coelom; such as flatworms.

Class Turbellaria

Class of free-living flatworms, commonly called planarians.

Class Trematoda

Class of parasitic flatworms, also known as flukes.

Class Cestoda

Class of flatworms known as tapeworms.

Ectoparasites

Parasites that live on the outside of their hosts.

Endoparasites

Parasites that live inside their hosts.

Scolex

The head of a tapeworm, equipped with attachment organs.

Proglottids

Segments of a tapeworm's body that contain reproductive organs.

Gastropoda

Class of mollusks that includes snails and slugs.

Bivalvia

Class of mollusks that includes clams and mussels, typically with two shells.

Cephalopoda

Class of mollusks that includes squid and octopus, known for intelligence.

Exoskeleton

A hard outer covering that provides support and protection.

Chitin

A structural polysaccharide that makes up the exoskeleton of arthropods.

Myriapoda

Subphylum of arthropods that includes millipedes and centipedes.

Diplopoda

Class of myriapods known as millipedes, with two pairs of legs per segment.

Chilopoda

Class of myriapods known as centipedes, with one pair of legs per segment.

Hexapoda

Subphylum of arthropods that includes insects, characterized by six legs.

Metamorphosis

The process by which insects develop from larvae to adults.

Complete metamorphosis

Life cycle in which the larval stage and adult stage are dramatically different.

Incomplete metamorphosis

Life cycle in which the larval stages resemble the adult.

Ecdysozoans

Animals that undergo ecdysis, or molting.

Class Clitellata

Class of annelids that includes earthworms.

Subclass Oligochaeta

Subclass of clitellata that contains earthworms.

Subclass Hirudinea

Subclass of clitellata that includes leeches.

Parasitic species

Organisms that live on or inside hosts and obtain nutrients from them.

Filtation feeders

Organisms that strain food particles from water.

Acoelomate

Organisms lacking a body cavity, such as flatworms.

Open circulatory system

A circulatory system where blood is not always contained within vessels.

Closed circulatory system

A circulatory system where blood remains in vessels at all times.

Adaptive value

A trait that increases an organism's chances of survival and reproduction.

Coral bleaching

Loss of symbiotic algae in coral, often caused by environmental stress.

Adaptive value of external fertilization

Allows for a large number of offspring and higher genetic diversity.

Cnidarian characteristics

Diploblastic, radial symmetry, and a gastrovascular cavity.

Eumetazoans

Animals that have true tissues, including Cnidarians.