5.2.2. Cnidaria Flashcards
_____and ____ are the simplest living animals with true tissues and thus form the base of the evolutionary group _____—the “true animals; nearly all marine, with only a few known freshwater species of cnidarians
Cnidarians and ctenophores
Eumetazoa
Cnidaria is derived from the unique stinging cells, called ____, present on the body and tentacles of the members of this group.
cnidocytes
____ are commonly called comb jellies (or comb jellyfish)due to the presence of eight ciliated bands superficially resembling combs that encircle the body.
Ctenophores
“comb bearers”
Ctenophores
Ctenophores exchange gas through ___
simple diffusion
_____
-are nearly all carnivorous but do not actively pursue their prey.
-have ____symmetry
-lack any definite concentration of nervous tissue or sensory organs.
possess a _____ (majority nonpolarized) that connects the uniformly distributed sensory cells and motor neurons to enable a limited number of coordinated movements and behaviors through innervations of the longitudinal and circular “muscle” cells.
-___ arrangement, consisting of an outer epidermis and an inner gastrodermis.
Cnidarians
radial
nerve net
diploblastic
Cnidarians have two basic body forms____ and ____
polyps and medusae
- gelatinous layer between epidermis and inner gastrodermis
mesoglea
- central digestive cavity in gastrodermis; has only a single opening (mouth) for ingesting and excreting
gastrovascular cavity
-represented by a cylindrical organism that remains attached to the substrate by a short stalk and has a mouth that faces away from the substrate (usually upward).
polyp
______- more circular, umbrella shaped form with a mouth on the underside; generally are free floating with tentacles that hang downward, surrounding the mouth; body shape is maintained to some degree by the viscosity of the gelatinous mesoglea and by the regulation of fluid in the gastrovascular cavity, an example of a ____.
medusa
hydrostatic skeleton
In _____ the polyp is the predominant form in the life cycle
hydrozoans
Hydrozoans (Class Hydrozoa)
asexual reproduction in the ____ form and sexual reproduction in the ____ form
___ is the predominant body form
polyp; medusa
polyp
- polyps are assembled into colonies
Obelia
____-do not produce medusae; exist as single, mobile polyps that reproduce either sexually (through production of sperm and eggs) or asexually (through budding) producing a new polyp
Hydra
- the defining characteristics of cnidarians
- use these tiny cells both for capturing prey and also as a deterrent to predators
- line the tentacles and outer surface of the cnidarian body.
Cnidocytes
-a stinging capsule within each cnidocyte
Nematocyst
connected by branches of a common gastrovascular cavity (coenosarc), making them all part of a larger functioning body.
Colonial hydrozoans- Members of the genus Obelia
- This cooperative venture allows certain polyps to develop into highly specialized feeding polyps, and others to lose the ability to feed altogether in exchange for an enhanced ability to reproduce.
Coenosarc
____illustrates an alternation of the sexual (medusa)and asexual (polyp) stages commonly seen in hydrozoans.
Obelia
Each zygote develops into a ciliated, swimming ____ that settles to the bottom of the ocean floor, attaches itself to the substrate, and begins to create a new generation of polyps through asexual budding.
planula larva
thick layer of gelatinous mesoglea
True Jellyfish (Class Scyphozoa)
largest scyphozoans
Cyanea-
In _____, the medusa stage is dominant, with the polyp stage relegated to an inconspicuous, short lived larval form that matures quickly into a polyp that buds off young medusae.
Cyanea
- moon jellyfish; common genus
Aurelia
_____ are represented by sessile organisms in the ____ stage, existing as solitary individuals (sea anemones) or as true colonies of dozens to thousands of individuals (corals)
life cycle does not include a free swimming ___ stage.
the most numerous and most specialized
Anthozoans
polyp
medusa
- common North Atlantic sea anemone
Metridium
species of small, marine invertebrates with transparent, bioluminescent, gelatinous bodies commonly referred to as ____” “sea walnuts,” or simply ctenophores.
“comb jellies,
is derived from the unique distinguishing characteristic that all members of the phylum
possess—eight rows of evenly spaced ciliated bands (_____) that encircle the body longitudinally
most species possess either a pair of tentacles or oral lobes that are used to collect food but lack the ____
these carnivorous predators capture prey by discharging a ____ from specialized cells
have a decentralized nerve net without a brain, and the body wall is composed of two layers: an ___ and ___
Comb jellies phylum Ctenophora comb plates stinging cnidocytes sticky adhesive outer epidermis and inner gastrodermis
Do/Are Comb jellies ____
have a complete digestive system?
monoecious (hermaphroditic)/ dioecious?
Yes. they have complete digestive system
monoecious
- gelatinous layer similar to mesoglea sandwiched between the two tissue layers.
collenchyme
-an animal’s response to stimuli in its environment
Behavior
-basic physiological unit of behavior; consists of sensory structures, neurons, and muscles (or glands) whose actions are coordinated to bring about certain behaviors.
motor system
-is the series of immediate physiological events that led up to the specific behavior; explaining how the behavior occurs
proximate cause
-the resultant selective advantages that have promoted that behavior to remain in the animal’s repertoire of possible responses and to evolve over time; explaining why the behavior exists
ultimate cause
Give four major classes of cnidarians
Hydrozoa
Scyphozoa
Cubozoa
Anthozoa
Complete the words (Hint: representatives/examples)
Hydrozoa: H___, O____, P____
Scyphozoa: J___ (Aurelia)
Cubozoa: Box jellyfish (C____)
Anthozoa: S____ (Metridium), c____, sea fans
Hydra, Obelia, Portuguese man of war
Jellyfish (Aurelia)
(Chironex)
Sea anemones (Metridium), corals, sea fans
Alternation of polyp and medusa stages in most species, medusa has velum, mostly marine with a few freshwater species, colonial or solitary
Hydrozoa
Solitary, free floating medusa most prominent form, medusa without velum, mostly marine, mesogleal layer generally thick
scyphozoa
Solitary, free swimming, medusa most prominent form, medusa has velarium (similar to hydrozoan velum), small body (generally 2–3 cm) with square shaped bell, tropical or subtropical
Cubozoa
No medusa stage—polyp stage predominates life cycle, entirely marine, may be colonial or
solitary, gastrovascular cavity divided by septa into chambers to increase digestive surface area
Anthozoa
(Hydra anatomy)
Defense and prey capture
Tentacles
(Hydra anatomy)
Ingestion of food and elimination of indigestible particles (egestion)
Mouth
(Hydra anatomy)
Elevated mound of tissue that expands or contracts to regulate size of mouth opening
Hypostome
(Hydra anatomy)
Specialized stinging cells located in the epidermal layer of the tentacles and body wall
Cnidocytes
(Hydra anatomy)
Chamber within which extracellular digestion of prey occurs; only opening is through the mouth
Gastrovascular cavity
(Hydra anatomy)
Product of asexual reproduction; will fall off when mature and become a self sufficient organism
Bud
(Hydra anatomy)
Organs for sexual reproduction; Hydra are dioecious, meaning that an organism has either testes or ovaries
(male or female), but not both
Gonads (testes and ovaries)
(Hydra anatomy)
Specialized region for attachment to the substrate
Basal disc
(Hydra anatomy)
Outer tissue layer; specialized for protection
Epidermis
(Hydra anatomy)
Inner tissue layer; specialized for digestion
Gastrodermis
(Hydra anatomy)
Inert, acellular, jellylike substance that aids in supporting the body
Mesoglea
(Anatomy of Obelia)
Polyp specialized for food acquisition
Hydranth (feeding polyp)
(Anatomy of Obelia) Polyp
Polyp specialized for reproduction
Gonangium (reproductive polyp)
(Anatomy of Obelia) Polyp
Product of asexual reproduction;medusae will be released from the gonangium
when mature and will produce either sperm or eggs, which fuse with the respective
gamete forming a zygote that will develop into a new polyp
Medusa buds
(Anatomy of Obelia) Polyp
Common chamber within which extracellular digestion occurs; nutrients are
distributed throughout organism
Coenosarc
(Anatomy of Obelia) Polyp
Translucent outer covering of organism; serves protective function
Perisarc
(Anatomy of Obelia) medusae
Stalk of fleshy tissue that supports the mouth
Manubrium
State the structures in the Polyp of Obelia (7) and Medusa of Obelia(4)
Polyp:
Hydranth (feeding polyp); Tentacles; Hypostome; Gonangium (reproductive polyp); Medusa buds; Coenosarc; Perisarc
Medusa:
Tentacles: Manubrium; Mouth; Gonads
(Anatomy of Aurelia)
Provide sensory information and used in defense and locomotion
Marginal tentacles
(Anatomy of Aurelia)
Defense and prey capture
Oral arms
(Anatomy of Aurelia)
One of four divisions of the gastrovascular cavity for digestion of food
Gastric pouch
(Anatomy of Aurelia)
Extensions of the gastric pouches that radiate outward from the pouches and distribute nutrients through
out body
Radial canals
(Anatomy of Aurelia)
Circular extension of the gastric pouches that distributes nutrients to outer rim of jellyfish
Circular canal
(Anatomy of Metridium)
Raised portion of the mouth (equivalent to the hypostome of hydrozoans)
Oral disc
(Anatomy of Metridium)
Pore that allows circulation of fluids between adjacent body sections
Ostium
(Anatomy of Metridium)
Muscular portion of the gastrovascular cavity for pulling prey inward and expelling indigestible particles
Pharynx
(Anatomy of Metridium)
Expand and contract the body
Retractor muscles
(Anatomy of Metridium)
Specialized chamber for extracellular digestion of prey
Gastrovascular cavity
(Anatomy of Metridium)
One of six thin, vertical walls that divides body into sections, providing support and increased surface area
for digestion
Primary septum
(Anatomy of Metridium)
One of several thin, incomplete vertical walls that further subdivides body, providing support and increased
surface area for digestion
Secondary septum
(Anatomy of Metridium)
Tough, fleshy base that attaches organism to rocks or sandy ocean floor; most anemonescan use this
to move slowly, gliding along the ocean floor
Pedal disc
(Anatomy of Metridium)
Contain cnidocytes and may be extended through the mouth to aid in subduing live prey or to provide
additional defense against predators
Acontia
