2. Animal Diversity Flashcards
Diplontic life cycle
refers to the life cycle of organisms which is dominated by the diploid stage
asymmetry
the lack or absences of symmetry
radial symmetry
symmetry in which the body is shaped like a pie or barrel (lacking a left side & right side) and can be divided into mirror imaged halves
oral-aboral axis
the establishment. maintenance and elaboration of a line that delineates the mouth and the anus of an embryo
bilateral symmetry
body symmetry in which a central longitudinal plane divides the body into two equal but opposite halves
cephalization
an evolutionary trend toward the
[ ] of sensory equipment at the anterior end of the body
anterior
the front/head of a bilaterally symmetrical animal
posterior axis
the rear/tail end of a bilaterally symmetrical animal
dorsal axis
the top of an animal with radial or bilateral symmetry
ventral axis
the underside/bottom of an animal with radial or bilateral symmetry
diploblastic
having 2 germ layers
triploblastic
having 3 germ layers
- the endoderm
- mesoderm
- ectoderm
endoderm
the innermost of the 3 primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs and the lining of the digestive tract
mesoderm
the middle primary germ layer in a triploblastic animal embryo; develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most circulatory system
ectoderm
the outermost of the 3 primary germ layers in animal embryos; gives rise to the outer covering and in so phyla the nervous system, inner ear and lens of the eye
coelom
a body cavity lined by tissue derived only from mesoderm
protostome
a developmental mode distinguished by the development of the mouth from the blastopore; often characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split
spiral cleavage
a type of embryonic development in protostomes where the planes of cell division that transform the zygote into a ball of cells are diagonal to the vertical axis of the embryo
Deuterostome
in animals a developmental node distinguished by the development of the anus from the blastopore;
radial cleavage
a type of embryonic development in deuterostomes where the planes of cell division that transform the zygote into a ball of cells are either parallel/perpendicular to the vertical axis of the embryo
invertebrates
an animals without a backbone
vertebrates
animal with a backbone
mesohyl
a gelatinous region between the two layers of cells of a sponge
totipotent
describing a cell that can give rise to all parts of the embryo and adult as well as extra-embryonic membranes in species that have them
pluripotent
describing a cell that can give rise to many but not all parts of an organism
gastrovascular cavity
a central cavity with a single opening in the body of certain animals (cnidarians, flatowrms) that functions in both the digestion and distribution of nutrients
epidermis
the outermost layer of cells in an animal
polyp
the sessile variant of the cnidarian body plan; the alternate form is the medusa
medusa
the floating, flattened, mouth-down version of the cnidarian body plan; alternate form is the polyp
cnidocyte
a specialized cell unique to the phylum Cnidaria; contains a capsule-like organelle housing a coiled threat that when discharged explodes outward and functions in prey capture/defence
blastopore
in the gastrula, the opening of the archenteron that typically develops into anus = deuterostomes; mouth=protostomes
water vascular system
a network of hydraulic canals unique to echinoderms that branches into extensions called tube feet which function in locomotion and feeding
notochord
a longitudinal, flexible rod made of tightly packed mesodermal cells that runs along the anterior-posterior axis of a chordate in the dorsal part of the body
mammary gland
an exocrine gland that secretes milk to nourish the young; and is a characteristic of mammals
trochophore
distinctive larval stage observed in some lophotrochozoan animals
visceral mass
one of three main part of a mollusc containing most of the internal organs
mantle
one of the three main parts of a mollusc; a fold of tissue that drapes over the mollusc’s visceral mass and may secrete a shell
mantle cavity
a water filled chamber that houses gills, anus and excretory pores of a mollusc
radula
a strap-like scraping organ used by many molluscs during feeding
cuticle
the exoskeleton of an arthropod, consisting of layers of protein and chitin that are variously modified for different functions
exoskeleton
a hard encasement on the surface of an animal (i.e shell of a mollusc, cuticle of an arthropod) that provides protection and points of attachment for muscles
moulting
a process in ecdysozoans in which the exoskeleton i shed at intervals, allowing growth by the production of a larger exoskeleton
chelicera
one of pair of clawlike feeding appendages character of chelicerates
complete metamorphisis
the transformation of a larva into an adult that looks very different and often functions very differently in its environment than the larva
incomplete metamorphisis
a type of development in certain insects (grasshoppers) in which the young resemble adults but are smaller and have different body proportions and go through a series of moults; each time looking more like an adult until it reaches full size
