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61 terms

BIOL 201 Chp 7: Cnidaria

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coelenteron
a blind, saclike cavity lined by gastrodermis and opening to the exterior via the mouth which functions in extracellular digestion, circulation, excretion, reproduction, and hydrostatic skeletal support
gastrovascular cavity
another name for a coelenteron
tentacles
arranged in one or more whorls that surround the mouth of a cnidarian
radial symmetry
a body plan where a vertical section along an axis or through any radius produces mirror-image halves
oral aboral axis
a body arrangement that extends from the mouth to the base
polyp
a body form of a cnidarian that resembles a flower and its stalk
pedal disc
a structure at the aboral end of a polyp used for attachment
manubrium
an elevated region, with the mouth at its summit, situated in the center of a cnidarian's oral disc
oral disc
the region of a cnidarian's body with the mouth and manubrium at its center, and a whorl of tentacles at its margin
periderm
a chitinous exoskeleton secreted by the pedal disc and column of a polyp that provides protection and attachment to the substratum
medusa
a body form of a cnidarian shaped like an umbrella or bell
subumbrella
the oral surface (disc) of a medusa's body
exumbrella
the aboral side of a medusa's body
epidermis
the outer epithelium of a cnidarian's body
gastrodermis
the inner epithelium of a cnidarian's body that lines the coelenteron
mesoglea
a gelatinous extracellular matrix between the epidermis and gastrodermis
stolon
a tubular body wall outgrowth that includes the coelenteron, from which zooids bud at intervals along its length
stolonate colony
a cnidarian growth form that consists of a single or branched tubular body wall outgrowth attached to the surface of the substratum, that grows in a two-dimensional network and bears upright, unbranched zooids
coenosarc
a continuous mat-like sheet of stolonate tissue that unites the zooids and attaches the colony to the substratum
solenia
a network of hollow gastrodermal tubes, located between the upper and lower epidermal surfaces of the coenosarc, that course through the mesoglea and interconnect the zooidal coelenterons
fruticose colony
an upright, plantlike cnidarian growth form that may be grassy, bushy, shrubby, or feathery in appearance
coronal muscle
the principal halo-shaped, circular muscle of medusae located on the subumbrellar surface
nerve net
a complex two-dimensional system of interconnected neurons located in the epidermis and gastrodermis, joined together by neurons in the mesoglea
diffuse conduction
the radiation of nerve impulses through a nerve net like ripples from a pebble tossed in a pond
ganglion
a brainlike concentration of neurons that receives sensory input, integrates the information with other inputs, and generates motor output
cnidocyte
a combined sensory-effector cell that plays a central role in prey capture and defense; a unique and defining feature of cnidarians
cnida
a fluid-filled membranous capsule containing a long tubular invagination of the capsule wall that, upon stimulation, everts explosively to the exterior to sting prey or to adhere to the surface of an animal or substrate
nematocyst
a type of cnida found in all cnidarians that has spines or barbs on the surface of the discharged tubule
spirocyst
a thin-walled cnida occurring only in anthozoans that contains a coiled, spring-like tubule that, when discharged, releases tiny, sticky threads
stomach
the central compartment in the cnidarian coelenteron
radial canals
the branches of the cnidarian coelenteron connecting the stomach to the ring canal
ring canal
the branch of the cnidarian coelenteron located around the margin of the body
enzymatic gland cells
the secretory cells lining the gastrodermis which release proteases that digest prey extracellularly
planula
the ciliated, free-swimming planktonic larva of cnidarians that settles to the bottom and metamorphoses into a juvenile
septa
the vertical partitions of gastrodermis and mesoglea that divide the anthozoan coelenteron into radial compartments
acontia
the long, threadlike, cnidae-bearing extensions of the septa which spew from the mouth and tentacle tips when the body suddenly deflates; used for defense, prey capture, and extracorporeal digestion of prey
retractors
the strongly-developed and conspicuous longitudinal septal muscles of anemones which, upon contraction, invaginate the oral disc and tentacles and shorten the body column
pedal laceration
a specialized form of fragmentation in anemones where small pieces of the pedal disc detach and develop into small anemones
corallite
the skeletal cup around the polyp of a stony coral, which the polyp can retract into for protection
bleaching
the process where zooxanthellae corals expel some or all of their algae due to adverse conditions such as under- or overillumination, excess UV exposure, salinity fluctuation, and low or high temperatures
Medusozoa
the taxon that includes cnidarians with a medusa stage in their life cycle, such as Scyphozoa and Hydrozoa
scyphistoma
the small, funnel-shaped polyp found in large jellies
septal funnel
a hollow invagination of the oral disc extending deeply into the septa of large jellies
oral arms
four divisions of the manubrium of large jellies that extend below the bell
gastric filaments
the slender, threadlike clusters found at the septal margins of large jellies that bear nematocytes and enzymatic gland cells used in subduing prey and digestion
lappets
the rounded, scalloped lobes on the umbrellar margin of large jellies which provide flexion points during bell contraction
rhopalia
the knoblike sensory organs of large jellies consisting of a statocyst, a mechanoreceptor, and a chemoreceptor (and sometimes a photoreceptor); provide information related to gravity-equilibrium, waterborne vibrations (hearing), as well as odor and light detection
strobilation
the process where scyphistomae asexually reproduce young medusae
strobila
a scyphistoma that is asexually-producing disclike medusa from its oral end
ephyra
in scyphozoans, the newly released, free-swimming, juvenile medusa
hydranth
a polyp of colonial hydrozoans, each containing a mouth, manubrium, tentacles, and stomach
velum
an iris diaphragm located below the bell of a hydrozoan medusa that creates a powerful water jet as the jelly swims
hydroids
the sessile, benthic colonies of hydrozoans
gastrozooids
the typical feeding hydranths of colonial hydrozoans
gonophores
the incompletely differentiated medusae of colonial hydrozoans that produce gonads, but lack some or most other medusan traits
medusa buds
produce free-swimming medusae in colonial hydrozoans
dactylozooids
the protective or food-catching polyps of colonial hydrozoans that contain batteries of nematocytes
pneumatophore
a gas-filled float in siphonophores that provides buoyancy
Anthozoa
a class of cnidarians including the sea anemones, corals, sea fans, sea pens, and sea pansies
Scyphozoa
a class of cnidarians including the large jellyfish, as well as box jellies, stalked jellies, flag-mouth jellies, and root-mouth jellies
Hydrozoa
a class of cnidarians including the colonial hydroids, Portuguese man-of-war, fire corals, and rose corals, as well as the solitary Hydra