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1. Explain why the distribution of benthic biomass mirrors the distribution of chlorophyll (i.e. primary production) in surface waters. (Also see fig. 15.1)

Life on the ocean's floor depends on the productivity of the primary producers; therefore shallow waters with photosynthesis, allow for more primary production for benthic life below them.


. Contrast the diversity of intertidal regions with other benthic environments

The greatest animal diversity is in the low tropical
diversity of algae is greater in the middle latitudes
rocky intertidal have moderate diversity


Describe the varying degrees of exposure to the atmosphere experienced by organisms in the intertidal zone, i.e., high, middle, and low tide zones.

high tide zone - relatively dry, covered with highest high tide
middle tide zone - covered with all high tides, exposed during all low tides
low tides - usually wet, but exposed during the lowest low tides


describe how shelled organisms like opihi prevent drying out during low tide.

ability to seek shelter within a shell
thick exterior or skeleton to prevent water loss
external surfaces covered by shell of rock to prevent water loss
adapted to a period of drying out without dying


List adaptations that enable organisms to live in the high tide zone

protective covering which prevents water loss
thick cell walls
able to attach themselves to rocks


Explain why more types of soft-bodied organisms live in the middle tide zone compared to the high tide zone.

seawater constantly bathes the middle tide zone


Give a commonly recognizable feature of the middle tide zone

mussel beds


List the common middle tide zone predators

carnivorous sea snail and sea star


Which common middle tide zone predator is related closely to marine jellies

sea anemone


Explain why marine algae and plants are common in the low tide zone

low tide zones are typically always submerged


Name a dominant second trophic level organism that feeds on marine algae.

hermit crab


Explain why marine organisms in sediment-covered coastal habitats require different adaptation than organisms in rocky shorelines

sediment covered shores are composed of unconsolidated material which is always changing shape and so require specific adaptations


Contrast biodiversity and species abundance on sediment-covered and rocky coastal habitats

there is less species diversity, but the organisms are found in greater numbers.


Explain the dominance of infauna in sediment-covered coastal habitats.

they can burrow into the sediment


List the different sediment-covered coastal habitats in the order of progressively lower energy and finer sediment size.

coarse boulder beaches, sand beaches, salt marshes, mud flats


Explain why decomposition is higher in sandy coastal habitats compared with salt marshes

water from breaking waves provide oxygen and nutrients which help breakdown dead material. the sediments are not rich in salt marshes as it is in sandy costal habitats


Describe the sediment-covered coastal habitat where intertidal zonation is best developed

supratidal, high tide, middle tide, low tide


Explain why most sandy beach organisms burrow into the sand

there is no stable fixed surface for the organism to attach to


Define bivalve

an animal with two hinged shells


Explain why bivalves have a depth limit for burrowing into the sediment.

bivalves can only burrow deep enough where their siphon is able to reach the surface for water, food, and oxygen


Define crustaceans

long segmented body, with hard exoskeletons, and jointed limbs


List several crustaceans that inhabit coastal habitats

beach hoppers, sand crabs, barnacles, and shrimp


Define echinoderms

spiky skin that live in beach deposits, (sea stars)