Introduction to the Animal Kingdom & Sponges

Flashcards covering the introduction to the Animal Kingdom, characteristics of animals, different feeding strategies, branches of the animal kingdom, possible animal ancestry, key concepts in embryonic development, and foundational information about sponges.

Domain Eukarya

The domain that animals belong to, characterized by eukaryotic cells.

Multicellular Organisms

Organisms composed of more than one cell; a characteristic of animals.

Heterotrophs

Organisms that must acquire nutrients from an external source, unlike autotrophs.

Herbivores

Animals that primarily consume plants or algae for energy.

Carnivores

Animals that primarily consume other animals for energy.

Omnivores

Animals that consume both other animals and plants for energy.

Detritivores

Animals that consume decomposing dead organic matter; a type of decomposer.

Invertebrates

Animals that lack a spine or vertebral column, making up 97% of animal species.

Vertebrates

Animals that possess a spine or vertebral column, making up 3% of animal species.

Motile Protozoan Ancestor

The single-celled, mobile, animal-like protist ancestor from which animals are thought to have evolved.

Protozoan

An animal-like protist that is heterotrophic.

Choanoflagellate

A currently existing group of motile protozoans that the single-celled ancestor of animals is thought to have resembled due to molecular, morphological, and behavioral reasoning.

Choanocytes

Specialized cells found in sponges that directly resemble choanoflagellates, providing strong evidence for the animal ancestry hypothesis.

Phylogeny

An evolutionary tree illustrating the relationships between different groups of organisms.

Asymmetry

A total lack of symmetry; characteristic of the entire group of sponges among animals.

Radial Symmetry

An animal body plan organized circularly, where multiple planes can divide the animal into equivalent halves (e.g., cnidarians, ctenophores).

Bilateral Symmetry

An animal body plan having equal left and right halves; characteristic of most animals, including vertebrates.

Protostomes

A group of triploblastic animals in which the mouth develops first during embryonic development; most invertebrates are protostomes.

Deuterostomes

A group of triploblastic animals in which the anus develops first during embryonic development; includes all vertebrates.

Germ Layers

The first tissue layers that develop during embryonic development in animals.

Tissue

A group of related cells that perform a specific function.

Diploblastic Animals

Animals whose embryos have only two tissue layers (ectoderm and endoderm) during embryonic development; they lack true specialized organs (e.g., cnidarians, ctenophores).

Ectoderm

One of the two primary germ layers in diploblastic animals, or the outermost layer in triploblastic animals.

Endoderm

One of the two primary germ layers in diploblastic animals, or the innermost layer in triploblastic animals.

Triploblastic Animals

Animals whose embryos have three tissue layers (ectoderm, mesoderm, and endoderm), allowing them to develop specialized organs.

Mesoderm

The third embryonic tissue layer found in triploblastic animals, from which organs develop.

Cleavage

The first developmental event after fertilization, involving cell division without growth.

Fertilization

The fusion of a sperm cell with an egg cell, which produces a zygote that develops into an embryo.

Spiral Cleavage

A type of cleavage seen in most protostomes, characterized by cells stacking in a spiral pattern and having a determinant cell fate.

Determinant Cell Fate

Also known as a fixed cell fate; a characteristic of protostome development where each embryonic cell has a predetermined developmental path and can only develop into one specific part of the animal.

Radial Cleavage

A type of cleavage seen in deuterostomes, characterized by cells stacking in a radial pattern and having an indeterminate cell fate.

Indeterminate Cell Fate

A characteristic of deuterostome development where each embryonic cell is not predetermined as to what it will become, and if separated, each cell could potentially develop into a complete organism.

Blastula

A hollow sphere of cells that forms during early embryonic development.

Blastopore

An indentation or opening in the blastula that forms during embryonic development.

Coelom

A body cavity lined by mesoderm found in some protostomes and all deuterostomes.

Sponges (Phylum Porifera)

Often described as the simplest invertebrates, forming the base of the animal tree of life; they are multicellular but lack true tissues.

Pores

Numerous openings on the body of sponges that allow water to move through for feeding and respiration.

Osculum

The large opening at the top of a sponge through which water exits after being filtered.

Filter Feeder (Suspension Feeder)

A feeding strategy used by sponges, where they filter small food particles from water currents.

Sessile

Describes adult sponges as typically immobile, remaining attached to a substrate.

Sponge Larvae

The juvenile, motile form of sponges, which are capable of movement.