Exam #2 Flashcards
Cnidarians
-class Hydrozoa
-class Scyphozoa
-class Cubozoa
-class Anthozoa
Order Milleporina
fire corals, false corals
Order Stylasterina
lace corals
Order Siphonophora
Portuguese man o’war
Characteristics of Hydrozoa
-displays either polyp, medusa, or both
-mesoglea is never cellular
-gastroderm lacks nematocysts
Hydrozoans can be ___ but most are ___.
solitary, colonial
Exhibit polymorphism
dactylozooid, gastrozooid, and gonozoid
Fire corals
-retains characteristics of class Hydrozoa
-colonial calcareous hydrozoan
-unique from most hydrozoans in that a calcareous skeleton and is considered a stony coral
calcium crystal is _____.
aragonite
pores contain one of two different kinds of polyps ->
gastrozooid or dactylzooid
polyps are contained in pores called ________
gastropods and dactylopores
Pores and polyps are arranged in a ____ with ____ surrounding a gastropore in a circular fashion
cylosystem, dactyolopores
Milleporina contain ____
zooxanthellae
____ are mouthless and are arranged around the ____ ; main source of prey capture
dactylozooids, gastrozooids
Lace corals
-genus distichophora, stylaser
-thick layer of tissue overlying skeleton
-pores are star-shaped
-all members have fragile branched colonies
-do not build reef and do not contain zooxanthellae
-calcium crystal is either aragonite or calcite
-lack free medusa stage
____ capture prey, bend downward and deliver prey to ______.
dactylozooids, gastrozooid
Siphonophores
-exist as large pelagic colonies composed of polypoid and medusoid individuals
-many species have a gas-filled sac that acts as a float
-effective predator in the ocean
-most are bioluminescent
-some have lures
-can deflate to sink below the surface
Milleporina
-possess one type of cnidocyte
-contain zooxanthellae
-mustard color with white tips
-do not contain distinct cups or calices
Praya
may be one of the longest organisms on earth
Body plan of siphonophores
pneumatophore, nectophore/nectosome, siphosome, palpons
pneumatophore
gas-filled float
nectophore/nectosome
powerful medusae specialized for moving the colony through the water
siphosome
contains gastrozooids, dactylozooids, and “gonozooids”
palpons
thought to play excretory or defensive role
physonect
all three
cystonect
differs by not having a nectosome
calycophoran
differ in that they dont have a pneumatophore
Reproduction in siphonophores
-an egg gives rise to larval polyp
-this polyp gives rise to the float and forms budding zones
-from these budding zones, the other members of the colony develop always attached to the original
class cubozoa
box jellies, chironex fleckeri - sea wasp
Characteristics for Cubozoa
-square shape
-four evenly spaced tentacles or groups of tentalces
-approx. 20 species known
-have eyes
-24 eyes
-there is one rhopalia on each side of the box-shaped bell, four in all
-they alternate with the tentacles
eyes
-located on the rhopalia which are marginal sense organs which hang from the bell on stalks and are wifhed down by a statolith
-the function for the statolith is not known but it has been proposed as both a gravity-sensing organ and as a weight to keep eyes oriented regardless of body orientation
pit eye and slit eye
on each of the rhopalia there are two lensed eyes (large and small complex eye) an identical pair of pit-shaped ocelli (pit eyes) and an identical pair of slit-shaped ocelli (slit eyes)
Cubozoa reproduction
-sexual reproduction
-fertilization takes place inside the female after a male has passed a sperm packet with his tentacle
-eggs develop into planula
-after a few days as free-swimming planula, they settle and develop into polyps
-after a few months of feeding, polyps metamorphose into a single medusa
Cubozoa venom
-the most deadly in the animal kingdom
-500,000 nematocysts/tentacles
-toxicity and amount of venom vary per species
-cubozoas are active predators
Class Scyphozoa
-frequently referred to as jellyfish
-typically possess tentacles and most with nematocysts
-medusa stage is dominant stage and polyp form is reduced to a small larval stage
Characteristics of Scyphozoa
-one sessile order
-gonochoric
-lack a velum which is the shelf of tissue around the the margin of the bell of the hydrozoan and cubozoan medusae
-most are dioecious
The ____ may reproduce asexually by ____ or ____ of cysts.
scyphistoma, budding, formation
primary microplastics
pieces of plastic less than 5 mm long; some are “micro” by design such as those used in cleansers; nurdles are included
secondary microplastics
results of bigger plastic pieces weather down
____ has been shone to be lethal to juvenile corals
Oxybenzone (BP-3)
Zooxanthellae
dinoflagellate, are able to soak up the toxin but corals without the symbiont feel the full affects of the toxin which is “activated” by sunlight (oxybenzone is designed to dissipate light energy as heat but cnidarians metabolize oxybenzone in such a way as to form damaging radicals when exposed to sunlight).
Coastal developments and corals - How?
o Habitat degradation
o Sand erosion, land retreat, and sedimentation
o Changed water flows
o Chronic runoff
o Sewage effluent
o EDCs and the microbiome
Two ways the sea can rise…
thermal expansion and increased melting of ice sheets
What’s in it for the Zooxanthellae?
- Protection
- A constant environment
- Nitrates, phosphates and ammonia
What’s in it for the polyp?
- Nutrients from photosynthesis
- Calcification
- Zooxanthellae remove the carbon dioxide that is an end product of calcification
Symbiosis
- Parasitism
- Commensalism
- Mutualism
Algal-invertebrate symbiosis
- Most hermatypic corals are symbiotic with a dinoflagellate called zooxanthellae
- Soft corals, jellyfish, giant clams, sponges, protists and nudibranchs also have evidence of this symbiosis with zooxanthellae
- Cyanobacteria have been discovered to coexist with zooxanthellae in Montastrea cavernosa
Polyps can control the amount of ____ that occurs by the distance they extend their tentacles
photosynthesis
Coral brooders can endow their ____ with a starter culture; broadcast spawners must incorporate free-living dinoflagellates
planula