Jennie Moran

Clay Campbell

Sandy Intertidal Zone Outline

I. Sandy Intertidal Zone

A) Intertidal zone is the range between the highest and lowest extent of the tides

B) Sandy intertidal zones are characterized by the presence of small fine sediments in an intertidal zone

C) Vertical Zonation- organisms are generally found only in specific vertically defined areas due to environmental constraints.

II. Organisms v. Environment

A) Envrionmental Constraints

1. Salinity-

a. Increase from tide coming in as organisms are submerged or evaporation in tidepools

b. Decrease from freshwater runoff or tide going out as organisms are left exposed

2. Temperature-

a. Increase since tidepools warm faster than deep water or as the tide goes out and organisms are exposed to direct sun

b. Decrease as tide comes in and organisms are submerged

3. Desiccation-

a. Increase as salinity and temperature factors increase

b. Decrease as salinity and temperature factors decrease

4. Food Consumption/Respiration/Photosynthesis

a. Increase as tide comes in and organisms can use oxygen in water to respire or photosynthesize, and can look for food

b. Decrease as tide goes out and organisms no longer have access to oxygen in water for respiration and photosynthesis, and can’t look for food

5. The extent of these constraints varies by location

a. geographically in the sense of climate, weather conditions, and water temperature

b. vertically by the extent of exposure created by tide change

B) Organism Response

1. Salinity

a. a. Motile organisms can travel from pool to pool if conditions become intolerable

b. organisms regulate osmotic diffusion of water to prevent detrimental changes in cell salinity

2. Temperature

a. Surface to volume ratio: greater surface area to volume ratio increases heat loss and absorbance

b. Evaporative cooling: evaporation requires heat energy to be used causing cooling

c. Circulation of body fluids: aids in heat distribution and diffusion

d. Burrowing: organisms can burrow into the sand or hide in other sheltered locations that will both retain water and reduce exposure to sunlight

3. Desiccation

a. Shells: many organisms retain water in their shells to prevent drying out

b. Burrowing: organisms can burrow into the sand or hide in other sheltered locations that will both retain water and reduce exposure to sunlight

c. Motile organisms can travel from pool to pool if conditions become intolerable

4. Food Consumption/Respiration/Photosynthesis

a. Reduction in metabolic rate to reduce the need for respiration resources

b. Organisms often forage only at certain times during the tide change to reduce exposure to predators

c. Predators often forage at times when their prey have slowed metabolic processes to conserve energy

5. The extent of adaptations necessary are dependant on location

a. geographically in the sense of climate, weather conditions, and water temperature

b. vertically by the extent of exposure created by tide change

III. Organisms found in Sandy Intertidal Zones

A) Plankton

B) Seaweed/Seagrasses

C) Algae

D) Shore birds

E) Fish

F) Jellyfish

G) Worms

H) Invertibrates

I) Mollusks

J) Gastropods

K) Crabs/Crustatians/ Arthropods