2. Shoreline between the high and low tide marks
Affected by tides and waves
Faces exposure to air/ emersion
a. k. a. Littoral region
Easily accessible; most-studied; best-understood
Based on substrate:
1. Rocky
2. Sandy
3. Muddy

3. Stephenson (1953)
Characteristic feature of Intertidal region
Def: a species predominate in a narrow horizontal
band of the shore, several such bands lie adjacent
to each other.
Most distinct on Rocky shores
Cause: different duration of submergence
vertical gradient of environmental
conditions
difference in ability of organisms to adapt

4. 3 universal zones:
I. Upper Intertidal region
II. Middle Intertidal region
III.Lower Intertidal region
 general rule: upper limit physical factors
lower limit biological
factors

5. Zonation is very prominent (on even surface) and depends on
the range of tidal region
‘quite similar in its general nature but highly variable in its
particulars’
Upper Intertidal region:
• ‘splash zone’: waves
• ‘black zone’: Lichens (Verrucaria)
• Upper part : turf of cyanobacteria (Calothrix)
• Snails (Littorina) dominate the shores; feed on algae
• Sea lice (Ligia) & Limpets (Acmaea) are also present
• Others: rats, shore crabs, oyster catchers, etc.

6. Middle Intertidal region:
• Experiences regular exposure to air and
submersion
• Divisible vertically into several regions
• Upper portion: Littorines, oysters(sand-stone),
barnacles (granite)
• Middle portion: Balanus, ostrea, cellana, mytilus,
ulva
• Lower portion: patches of algae, sea stars

7. Lower intertidal region:
• Immersed most of the times
• Extension of sub-tidal region
• Dominated by seaweeds: Sargassum,
Gracilaria & Laurencia
• Others: sea anemone, hydroids, chitons,
crabs, neries worm, fishes, etc.

8. Zonation isn’t prominent, as organisms live buried
in the substratum, also because zonation is
widespread
Dahl
 Upper intertidal region: talitrid amphipods and
ocypode crabs (scavengers)
Middle intertidal region: Amphipods (Urothoe),
Isopods (Eurydice), Polychaetes (Glycera,
Arenicola, Pectinaria, etc.), Bivalves (Donax,
Cardium, etc.)

9. Lower intertidal region: anomuran crabs (Albunea,
Emerita, etc.), Razor clam (Ensis), Sand mason
worm (Lanice), Heart urchin, etc.
Other Visitors:
• Birds: Sandpipers, Sea gulls
• Horse shoe crabs
• Grunion fish
• Sea turtles

10. Only shore with phanerogam flora
upper intertidal region:
1. Salt Marshes: Temperate
2. Mangrove swamps: Tropics
Salt marshes:
• Shelter from wave action and supply of silt & clay
• Eelgrass (Zostera) & cordgrass (Spartina)
• Extensive beds of Salicornia above high water mark
• Fauna: birds, mammals, insects, fiddler crabs, etc.

11. Mangrove swamps:
• Pneumatophores (Avicennia)
• Viviparity (Rhizophora)
• Provides habitat for other fauna: crab, oysters,
littorines, birds, barnacles, etc.
Middle intertidal region:
• Bivalve colonies (Macoma, Tellina, etc.)

12. Lower intertidal region:
• Bivalvia (Mya arenaria)
• Polychaetes (Chaetopterus, Urechis)
• Anomuran crustacean(Upogebia)

13. A Textbook of Marine Ecology by Nair and
Thampy
Marine Biology eighth ed. by Castro & Huber
Marine Ecology by Moore