week 8 - intertidal zone Flashcards
intertidal
the region of shore that lies between the highest high tide and the lowest low tide
- determined by the amount of time spent above water
how is organism distribution controlled?
- physical conditions
- determines upper limit of organisms in each zone
-animals cant live above this - biological interactions
- determines lower limit of organisms in each zone
- predation affects where they live
levels of tide
- supratidal
- upper intertidal
- middle intertidal
- lower intertidal
- subtidal
physical conditions of intertidal zones
- waves
- bring nutrients and moisture
- can detach organisms from substrate - exposure time
- tissues will not function is dessicated - heat and cold
- temperature changes more extreme above water - substrate
- support very different communities with varying diversity and abundance - available space
- organisms need a place to live
biological interactions of intertidal zones
- predation
- terrestrial predators
- sea otters eat sea urchins
- sea urchins eat kelp - competition
- seawater brings nutrients to organisms, so space is the most contested resource
- some organisms live on top of other organisms (encrusting) - adaptation
- physiological and morphological ways to deal with physical challenges
barnacles (4 things)
- crustacean that is related to crabs and lobsters
- exclusively marine, tend to live in shallow and tidal water, typically in erosive settings
- sessile suspension feeders, and have two nektonic (active swimming) larval stages
- well adapted against water loss
- calcite shells are impermeable, and possess two plates which they can slide across their apertures when not feeding
periwinkle snail (4 things)
- mainly found on rocky shores in the upper and middle intertidal zone
- sometimes lives in small tide pools
- larger shell volume allows more water storage, which allows some species to resist desiccation longer
- will withdraw into its shell and start rolling, which may allow it to fall to the water
mussels (4 things)
- live in intertidal areas attached to rocks and other hard substrates by byssal threads located in the foot of the mussel
- shells are open when submerged to filter plankton from the water column
- shells are close up when the tide goes down to prevent dehydration
- sea stars are their major predators
limpets and chitons
LIMPETS - aquatic snails with a shell that is broadly conical in shape and has a strong, muscular foot
CHITON - shell composed of eight shell plates that overlap slightly at the front and back edges
- both are mobile grazers that feed on algae when submerged
- both clamp down (suction applied by their large foot) to avoid desiccation during times of exposure
crabs
store water in gill chambers and can move to concealed areas or into the water if necessary
sea anemones (4 things)
single polyps that are related to corals and jellyfish
- feed by using their tentacles to paralyze drifting by, grabbed and then consumed
- will close up tight when the sea water recedes during low tide
- helps prevent the sea anemones from drying out when exposed to air
starfish and sea urchins
echinoderms that have tiny tube feet to attach to surfaces
STARFISH - covers the creature with its stomach, digests the food, and then pulls its stomach in again
SEA URCHINS - have a round shell with spines ot protect them from predators
- mouth is underneath, and their main food is brown seaweed
- both animals either attach to rocks or move into tide pools to avoid desiccation
basics of macroalgae (seaweed) (5 things)
- they are photoautotrophic
- aquatic
- eukaryotes
- unicellular or multicelluar
they are not plants because they don’t have specialized tissues
subdivided into green, brown and red algae
green algae (chlorophyta) (4 things)
ancestor of this seaweed gave rise to terrestrial plants
- closest relation to terrestrial plants
- cell walls made of cellulose (like terrestrial plants)
- can overgrow and kill coral reefs
brown algae (phaeophyta) (4 things)
largest of all algal species (giant kelp can grow to hundreds of feet)
- largest component of kelp forest
- structurally most complex of all seaweeds
- most brown algae contain the pigment fucoxanthin, which is resonsible for the distinctive greenish brown color that gives them their name
