Bio Ch 28 Flashcards
Vertebrates
animals that at some stage of their lives have a spinal cord (backbone) running down the center of the back
Invertebrates
do not have a backbone
Larva
immature stage that typically lives in a different habitat and feeds on different foods than the adult
Metamorphosis
change in body form
Colonial flagellate hypothesis
states that animals are descended from an ancestor that resembled a hollow spherical colony of flagellated cells
Symmetry
pattern of similarity that is observed in objects
Asymmetry
lack of symmetry; seen in sponges that have no particular pattern to body shape
Radial symmetry
cnidarians and comb jellies exhibit this; bodies are organized circularly, similar to a wheel, such that any longitudinal cut through the central point produces 2 identical halves; many adult and immature/larval forms have this; allows an organism to extend out in all directions from one center
Bilateral symmetry
definite left and right half; only a single longitudinal cut down the centerline of the animal produces two equal halves; defined anterior and posterior ends; forward movement is guided with the anterior end
Cephalization
localization of a brain and specialized sensory organs at the anterior end of an animal
Germ layers
first tissue layers that appear; give rise to the organs and organ systems of complex animals
Diploblastic
animals such as the cnidarians, which as embryos have only 2 tissue layers (ecto/endoderm) are termed this; develop tissues but no specialized organs
Triploblastic
animals that develop specialized organs; have 3 tissue layers as embryos (ecto/meso/endoderm)
Protostomes
embryo’s mouth develops prior to the anus
Deuterostomes
embryo’s anus develops prior to the mouth
Cleavage
first developmental event after fertilization; cell division without cell growth; protostomes = spiral, determinate; deuterostomes = radial, indeterminate
Blastula
hollow sphere of cells; indentation that follows produces an opening (blastopore)
Coelom
body cavity lined by mesoderm; certain protostomes and all deuterostomes have this
True coelom
mesoderm cells line the body cavity completely
Sponges
only animals to lack true tissues and to have only a cellular level of organization; aquatic, largely marine animals that vary greatly in size, shape, and color
Spicules
endoskeleton of sponges contain these small, needle-shaped structures with 1-6 rays; type of these classifies sponges (bony, glass, spongin)
Comb jellies
phylum Ctenophora; solitary, mostly free-swimming marine invertebrates that are usually found in warm waters
Mesoglea
body of ctenophores made up of this transparent, jellylike substance
Colloblasts
most ctenophores do not have stinging cells and capture their prey by using sticky adhesive cells called this
Cnidarians
tubular or bell-shaped animals that reside mainly in shallow coastal waters; some freshwater, brackish, and oceanic forms are known; term derived from specialized stinging cells
Nematocyst
each cnidocyte has a fluid-filled capsule called this that contains a long, spirally-coiled hollow thread; discharged when the trigger of the cnidocyte is touched
Gastrovascular cavity
internal cavity of cnidarians; serves for digestion of food and circulation of nutrients; also serves as supportive hydrostatic skeleton
Hydrostatic skeleton
fluid-filled gastrovascular cavity also serves as a supportive this because it offers some resistance to the contraction of muscle but permits flexibility
Polyp
1 of 2 body forms of a cnidarian; mouth directed upward
Medusa
1 of 2 body forms of a cnidarian; mouth directed downward; has more mesoglea than other body form; tentacles are concentrated on the margin of the bell
Nerve net
interconnected nerve cells that allow transmission of impulses in several directions at once
Lophotrochozoa
most diverse of the protostomes; bilaterally symmetrical during at least 1 stage of their development; have 3 germ layers as embryos; as adults have the organ level of organization; some have a true coelom; 2 groups - lophophorans & trochozoans
Lophophorans
bryozoans, phoronids, and brachiopods (“crest-bearing”)
Trochozoans
flatworms, rotifers, mollusks, and annelids (“wheel”)
Bryozoans
aquatic, colonial lophophorans; colonies are made up of individuals called zooids (single members of a colony that cooperate together as a single organism)
Brachiopods
small group of lophophorans that have 2 hinged shells (top and bottom); affix themselves to hard surfaces with a muscular pedicle; use their lophophore to feed by filtering particles from the water
Phoronids
live inside a long tube that is formed from their own chitinous secretions; tube is buried in the ground and their lophophore extends from it; only 15 species worldwide
Flatworms
trochozoans with an extremely flat body; have a sac body plan with only 1 opening (mouth; incomplete digestive tract); have no body cavity
Hermaphroditic
monoecious; possessing both male and female sex organs and gametes in a single individual
Ganglia
collections of nerve cells that functions as the brain of planarians
Flukes
parasitic flatworms named for the organ they inhabit
Scolex
highly modified head region of a tapeworm that has hooks for attachment to the intestinal wall of the host and suckers for feeding
Proglottids
series of reproductive units located behind the scolex of tapeworms that contain a full set of female and male sex organs
Rotifers
trochozoans related to the flatworms; Leeuwenhoek viewed these and called them “wheel animalcules”; have a crown of cilia (corona) on their heads; when in motion the corona looks like a spinning wheel; corona serves as an organ of locomotion and also directs food into the mouth
Molluscs
2nd most numerous group of animals; inhabit a variety of environments, including marine, freshwater, and terrestrial habitats; diverse phylum includes chitons, limpets, slugs, snails, abalones, conchs, nudibranchs, clams, oysters, scallops, squid, and octopuses; 3-part body plan consisting of visceral mass, mantle, and foot
Mantle
covering that lies to either side of, but does not completely enclose, the visceral mass (internal organs)
Radula
rasping, tongue-like organ that bears many rows of teeth and is used to obtain food
Hemocoel
in molluscs, the heart pumps blood (hemolymph) through vessels into sinuses/cavities collectively called this; blue hemocyanin is oxygen-carrying pigment
Bivalves
clams, oysters, shipworms, mussels, scallops; two-part shell hinged and closed by powerful muscles; have no head, no radula, very little cephalization
Gastropods
largest class of mollusks; include slugs, snails, whelks, conchs, limpets, and nudibranchs; most are marine; some are terrestrial
Cephalopods
range in length from 2cm to 20m; examples = giant squid, octopus; “head-footed”; propel selves by jet propulsion of water
Annelids
segmented worms; earthworms, marine worms, leeches; only trochozoan with segmentation and a well-developed coelom
Segmentation
repetition of body parts along the length of the body
Hydrostatic skeleton
well-developed coelom is fluid-filled and serves as a supportive ___ ___; permits independent movement of each body segment (along with the partitioning of the coelom)
Setae
bristles that protrude from the body wall, can anchor the worm, and help it move; oligochaetes = few of these; polychaetes = many of these
Nephridia
excretory system in earthworms consists of paired these, which are coiled tubes in each segment; has 2 openings - one is a ciliated funnel that collects coelomic fluid; the other is an exit in the body wall
Clitellum
fused mid-body segment of an earthworm
Radioles
ciliated mouth appendages of marine polychaetes; Christmas tree worms, fan worms, and featherduster worms have these
Ecdysozoans
large group of protostomes including roundworms and arthropods
Roundworms
phylum Nematoda; nonsegmented worms prevalent in almost any environment; generally colorless and range in size from microscopic to 1m; have pseudocoeloms
Pseudocoelom
body cavity incompletely lined with mesoderm (occurs inside the body wall but not around the digestive cavity/gut
Arthropods
very large group of protostomes that have exoskeletons and jointed appendages; includes insects, crustaceans, millipedes, centipedes, spiders, and scorpions
Metamorphosis
drastic change in form and physiology that occurs as an immature stage (larva) becomes an adult; larva eats different food and lives in a different environment than does the adult
Crustacean
animal with a hard, crusty exoskeleton, which contains calcium carbonate in addition to the typical chitin
Centipedes
each of their many segments has a pair of walking legs; “hundred-leggers”
Millipedes
“thousand-leggers”; each of 4 thoracic segments bears one pair of legs, while abdominal segments have 2 pairs of legs; some secrete hydrogen cyanide
Insects
adapted for an active life on land, although some have secondarily invaded aquatic habitats; body divided into head, thorax, and abdomen
Tracheae
insects’ respiratory system begins with openings in the exoskeleton called spiracles; from there, air enters these small, branching tubules
Chelicerates
live in terrestrial, aquatic, and marine environments; 1st pair of appendages = chelicerae (feeding/defense); 2nd pair = pedipalps (varied functions); cephalothorax followed by abdomen with internal organs; ex = horseshoe crab
Echinoderms
primarily bottom-dwelling marine animals; 5-pointed radial symmetry; sea stars, sea cucumbers…
Ossicles
echinoderms have an endoskeleton of spiny, calcium-rich plates called this
Water vascular system
innovation of echinoderms; consists of canals and appendages that function in locomotion, feeding, gas exchange, and sensory reception
Sea Stars
1600 species that are commonly found along rocky coasts, where they feed on clams, oysters, and other bivalve mollusks; have tube feet & 2 stomachs (cardiac & pyloric)
Sieve Plate
AKA madreporite; where water enters the water vascular system in sea stars
