What is the majority of animal species?; Invertebrates (animals without a backbone).
What is the definition of an animal?; Multicellular, heterotrophic eukaryotes with tissue that develops from embryonic layers.
What are the five criteria that create a reasonable definition of animals?; Multicellular, heterotrophic eukaryotes; lack of cell walls; presence of nervous and muscle tissue; sexual reproduction; and formation of blastula.
How do animals obtain organic molecules?; Through ingestion, eating other organisms, or decomposing organic material.
What provides structural support for animal cells?; Extracellular proteins, especially collagen.
What are the two unique types of tissues in animals?; Nervous tissue for impulse conduction and muscle tissue for movement.
How do most animals reproduce?; Sexually, with a small flagellated sperm fertilizing a larger, nonmotile egg.
What is the diploid stage that usually dominates the life cycle of animals?; The zygote.
What is the name of the multicellular, hollow ball of cells formed during cleavage?; Blastula.
What is the proposed origin of the animal kingdom?; From a colonial, flagellated protist.
What is the estimated age of the colonial flagellated protist that is the ancestor of the animal kingdom?; Over 770 million years ago in the Precambrian era.
What group is the colonial flagellated protist related to?; Choanoflagellates.
What is the hypothesis for the origin of animals from a flagellated protist?; A colony of identical cells evolved into a hollow sphere, then specialized into two or more layers of cells.
How do plants generate their own organic molecules?; Through photosynthesis.
How do animals obtain their organic molecules?; They must ingest them either through eating other organisms or eating non-living organic material.
What is the mode of nutrition for fungi?; Heterotrophic, living on or near the food source and always digesting their food externally.
From what did fungi evolve?; Single cell flagellate Protista.
What are the key characteristics of animals?; Multicellular, heterotrophic eukaryotes.
How do animals store their carbohydrate reserves?; As glycogen (plants use starch).
What do animals use for impulse conduction and movement?; Nervous and muscle tissue.
What are the general challenges that all animals must solve?; Extracting oxygen from the environment, nourishing themselves, excreting waste products, and moving.
What provides a mechanism for long-term adaptation in animals?; Natural selection.
What is the traditional view of relationships among animal phyla based on?; Mainly on key characteristics of body plans and embryonic development.
What distinguishes the major grades in the traditional phylogenetic tree of animals?; Structural changes at four deep branches.
What is the first branch point in the traditional phylogenetic tree of animals?; It splits the Parazoa which lack true tissues from the Eumetazoa which have true tissues.
What are the members of the phylum Cnidaria and phylum Ctenophora known collectively as?; The Radiata.
What is the other major branch besides Radiata?; The Bilateria.
What type of symmetry does Bilateria have?; Bilateral symmetry with a dorsal and ventral side, an anterior and posterior end, and a left and right side.
What is cephalization?; An evolutionary trend toward the concentration of sensory equipment on the anterior end.
What does cephalization include?; The development of a central nervous system concentrated in the head and extending toward the tail as a longitudinal nerve cord.
How does the symmetry of an animal generally fit its lifestyle?; Radial animals are sessile or planktonic and need to meet the environment equally well from all sides, while actively moving animals are bilateral.
What are germ layers?; Concentric layers of embryonic tissue that form various tissues and organs.
What are radiata said to be?; Diploblastic because they have two germ layers.
What does the ectoderm give rise to?; The outer covering and, in some phyla, the central nervous system.
What does the endoderm give rise to?; The lining of the digestive tract and the organs derived from it, such as the liver and lungs of vertebrates.
What are bilateria said to be?; Triploblastic.
What is the third germ layer in bilateria?; The mesoderm, which develops into the muscles and most other organs between the digestive tube and the outer covering of the animal.
What are acoelomates?; Organisms with a solid body and lack a body cavity.
What is a pseudocoelom?; A body cavity that is not completely lined by mesoderm.
What are coelomates?; Organisms with a true coelom, a fluid-filled body cavity completely lined by mesoderm.
What are the functions of a body cavity?; Cushions the internal organs, functions as a hydrostatic skeleton, and enables the internal organs to grow and move independently of the outer body wall.
How are the coelomate phyla divided based on differences in their development?; Into protostomes and deuterostomes, based on differences in cleavage pattern, coelom formation, and blastopore fate.
What is spiral cleavage?; A type of cleavage in which planes of cell division are diagonal to the vertical axis of the embryo.
What is determinate cleavage?; A type of cleavage where the fate of each embryonic cell is determined early in development.
What is radial cleavage?; A type of cleavage in which the cleavage planes are parallel or perpendicular to the vertical egg axis.
What is indeterminate cleavage?; A type of cleavage whereby each cell in the early embryo retains the capacity to develop into a complete embryo.
When does coelom formation begin?; In the gastrula stage.
What is schizocoelous development?; Solid masses of mesoderm split to form the coelomic cavities in protostomes.
What is enterocoelous development?; Mesoderm buds off from the wall of the archenteron and hollows to become the coelomic cavities in deuterostomes.
What is the fate of the blastopore in many protostomes?; It develops into the mouth, and a second opening at the opposite end of the gastrula develops into the anus.
What is the fate of the blastopore in deuterostomes?; It usually develops into the anus, and the mouth is derived from the secondary opening.