Diversity in the Animal Kingdom and Taxonomy Review

Vocabulary flashcards covering animal diversity, biological classification schemes, taxonomic rules, levels of body organization, and key characteristics of major animal phyla based on lecture notes.

Phenetics

A classification scheme where organisms are grouped based on the total or relative number of shared characteristics.

Phylogenetics / Cladistics

A classification scheme where organismal relationships are based on evolutionary similarities and differences, delimiting taxa exclusively by holophyly.

Cladogram

A tree-shaped dendrogram that is interpreted to represent evolutionary relationships among organisms.

Monophyletic Group (Taxon 1)

A group of organisms consisting of a single ancestral species and all of its descendants.

Polyphyletic Group (Taxon 2)

A group of organisms containing members traced from separate ancestors, where the most recent common ancestor is excluded because it lacks the group's characteristics.

Paraphyletic Group (Taxon 3)

A group of organisms indicating a recent common ancestor and some, but not all, of its descendants.

Evolutionary Classification

A classification system (also called Darwinian classification) formulated by George Gaylord Simpson that uses phylogenetic relationships, progenitor-descendant relationships, and degree of evolutionary change.

Hennigian Systematics

An approach to phylogenetic systematics proposed in 1950 by German entomologist Willi Hennig.

Carolus Linnaeus

The father of modern taxonomy who established the binomial system of nomenclature and originally proposed two kingdoms: Kingdom Animalia and Kingdom Plantae.

Ernst Haeckel

The scientist who proposed the three-kingdom classification scheme by establishing Kingdom Protista to include single-celled organisms with plant-like and animal-like features.

Herbert Copeland

The scientist who proposed a four-kingdom classification system in 1938, creating Kingdom Monera for bacteria and blue-green algae.

Robert Whittaker

The scientist who proposed the five-kingdom system in 1969, adding Kingdom Fungi alongside Monera, Protista, Plantae, and Animalia.

Carl Woese

The scientist who proposed the six-kingdom scheme, organizing life into three domains: Bacteria, Archaea, and Eukarya.

Prokaryotic Cell

A simple unicellular organism that lacks a nucleus or membrane-bound organelles, storing its DNA in a central region called the nucleoid.

Eukaryotic Cell

A cell possessing a membrane-bound nucleus ('true kernel') and specialized membrane-bound compartments called organelles.

Autotrophs

Organisms that manufacture their own food through photosynthesis.

Heterotrophs

Organisms (also known as consumers) that cannot manufacture their own food and depend upon autotrophs for nutrition.

Protoplasmic Grade of Organization

The level of organization characteristic of unicellular organisms, where all life functions are confined within a single cell boundary.

Spherical Symmetry

Body symmetry where any plane passing through the center divides the body into equivalent or mirror halves.

Radial Symmetry

Body symmetry in which an organism can be divided into similar halves by more than two planes passing along its longitudinal axis.

Bilateral Symmetry

Body symmetry where an organism can be divided along the sagittal plane into two mirrored right and left halves.

Diploblasts

Animals with radial symmetry that develop two embryonic germ layers: an inner endoderm and an outer ectoderm.

Triploblastic Animals

Animals that develop three primary embryonic germ layers: ectoderm, mesoderm, and endoderm.

Coelom

A fluid-filled main body cavity lined with mesoderm that surrounds and contains the digestive tract and other internal organs.

Acoelomate

An animal that completely lacks a body cavity, where the blastocoel space is entirely filled with mesoderm.

Pseudocoelomate

An animal possessing a body cavity that is not derived from mesoderm, where the blastocoel is only partially filled by mesodermal cells.

Eucoelomate

An animal possessing a true body cavity fully derived from and lined by mesoderm.

Protostome

An invertebrate organism whose embryonic blastopore develops into the mouth before the anus.

Deuterostome

An organism whose embryonic blastopore develops into the anus, while the mouth forms secondarily on the opposite side.

Metamerism

The repetition of body segments along an animal's axis; individual segments are termed metameres or somites.

Homonomous Metamerism

A primitive form of segmentation in which all body segments or somites of an animal are structurally alike.

Heteronomous Segmentation

A type of segmentation where the body segments of an animal are structurally differentiated from one another.

Cephalization

The evolutionary process of specializing anterior segments to form a head that concentrates sensory organs and neural control.

Binomial System of Nomenclature

A scientific naming system that assigns each species a two-part Latinized name: a generic name (genus) and a specific epithet.

International Code of Zoological Nomenclature (ICZN)

The set of rules and recommendations managed by the International Commission on Zoological Nomenclature to ensure stability and universality in animal scientific names.

Principle of Coordination

An ICZN principle stating that establishing a name in a family, genus, or species group simultaneously establishes the name for taxa at other ranks within that same group.

Principle of First Reviser

An ICZN principle stating that when conflicting divergent acts are published simultaneously, the first subsequent author determines precedence.

Principle of Priority

An ICZN principle stating that the oldest correctly published scientific name for a taxon takes precedence over newer names.

Principle of Homonymy

An ICZN principle dictating that every taxon name must be unique, meaning junior homonyms cannot be used as valid names.

Species

The basic unit of biological classification and biodiversity, defined as the largest group of organisms capable of interbreeding to produce fertile offspring.

Protozoa

Unicellular eukaryotic organisms (derived from Greek 'protos' meaning first and 'zoia' meaning animal) performing all life functions within a single plasma membrane.

Metazoa

Multicellular animals that possess specialized reproductive cells and undergo embryonic development.

Holozoic (Phagotropes)

A nutrition method in protozoans involving the ingestion of particulate food via phagocytosis.

Saprozoic (Osmotropes)

A nutrition method in protozoans involving the absorption of soluble nutrients directly across the cell membrane.

Encystment

The process where a protozoan forms a protective cyst wall to survive harsh environmental conditions.

Sarcodina

A group of protozoans whose movement is powered by cytoplasm streaming that forms pseudopodia (e.g., Amoeba proteus).

Mastigophora

A group of protozoans that move using one or more long whip-like flagella.

Ciliophora

A group of protozoans that move using numerous short hair-like projections called cilia (e.g., Paramecium caudatum).

Sporozoa

A group of parasitic protozoans that lack specialized locomotory organelles in their mature stage (e.g., Plasmodium vivax).

Ostia

Tiny body pores in sponges through which water enters the internal canal system.

Osculum

A large opening on a sponge through which water is expelled from the body.

Choanocytes (Guanocytes)

Flagellated collar cells lining internal sponge cavities (spongocoel) that drive water currents through the filter-feeding system.

Somatic Embryogenesis

The development of a complete new sponge individual from aggregated cell fragments.

Asconoid

The simplest and most primitive sponge body design, featuring a tube-like shape and a continuous flagellated spongocoel.

Syconoid

A vase-shaped sponge body design derived from asconoid ancestors, possessing flagellated radial canals.

Leuconoid

The most complex sponge canal system, lacking radial symmetry and featuring numerous flagellated chambers.

Calcarea (Calcispongiae)

A class of sponges characterized by spicules made of calcium carbonate.

Hexactinellida (Hyalospongiae)

Glass sponges possessing six-rayed spicules composed of silicon dioxide (siliceous) forming an interconnected network.

Demospongiae

A large class of sponges containing siliceous spicules that are not six-rayed, often paired with organic spongin fibers.

Cnidocytes

Specialized cells in Cnidarians that contain stinging organelles called nematocysts.

Nematocysts

Stinging organelles found within cnidocytes of Cnidarians used for prey capture and defense.

Anthozoa

A class of Cnidarians comprising corals and sea anemones that completely lack a medusa stage in their life cycle.

Scyphozoa

A class of Cnidarians comprising free-swimming, bell-shaped jellyfish that lack a velum.

Phylum Platyhelminthes

A phylum of unsegmented, triploblastic, acoelomate, bilaterally symmetrical flatworms that represent the earliest animals with cephalization.

Rheoreceptors

Sensory structures found in flatworms that detect the direction of water currents.

Neodermata

A parasitic flatworm group characterized by a unique tegument layer, comprising Trematoda, Monogenea, and Cestoda.

Phylum Nematoda

A phylum of unsegmented, cylindrical roundworms possessing a pseudocoelom that serves as a hydrostatic skeleton.

Amphids

Anterior sensory depressions in nematodes used for chemical sensing in water.

Phasmids

Posterior chemosensory depressions present in certain classes of nematodes.

Class Aphasmedia

A class of nematodes lacking phasmids, possessing amphids and caudal adhesive glands, including parasites like Trichinella spiralis and Trichuris trichiura.

Class Phasmedia

A class of nematodes possessing pore-like amphids and phasmids, a well-developed excretory system, and no caudal adhesive glands.