Intertidal Life

Pender Island Intertidal Zone

Photos and text by Derek Holzapfel

By definition, this is the area above the water at low tide and below the high tide water line.  It can include sandy beaches, rock cliffs and  boulder strewn shores.

This area supports life that can tolerate the extremes of being dried, heated by the sun, frozen in the winter, and bashed by stormy wave action.

Intertidal Zones at Medicine Beach

Intertidal Zones at Medicine Beach

There are four Intertidal Zones

     1.  Splash Zone – which receives spray from breaking waves and is above high tide line

     2.  High Tide Zone – which is underwater at high tide

     3.  Mid Tide Zone – the area between the average high and low tides, covered and uncovered by water twice a day

     4.  Low Tide Zone – which is only exposed at low tide and for a longer period during the exceptional below low tides

For Beach Combers, there are several  Areas of Interest:

sand/shell beach is a good area to dig to see clams, shrimp, and worm species

rocks / boulders / crevices are shaded areas not dried or heated that will have unique wildlife and 

lots of varied life under rocks

tide pools offer a great spot to view anemones, sculpins, crabs, seaweeds

(It is recommended to use a polarizer filter for best photography results)

Blood Star at Brooks Point, photo by Julie Wilmott

Blood Star at Brooks Point, photo by Julie Wilmott

**Treat With Respect and Tread Carefully**

Remember to:

  • replace rocks
  •  avoid stepping on rocks covered with snails and other life
  • tread with caution in the fragile environment of the intertidal zone

The most common species found in the intertidal zone around the Penders:

Anemones

Aggregating Anemones

Aggregating Anemones

Barnacles

Thatched Acorn Barnacle

Thatched Acorn Barnacle

– Acorn Barnacle and Thatched Barnacle

Beach Hoppers

California Beach Hopper

California Beach Hopper

Clams / Oyster

Pacific Littleneck Clam

Pacific Littleneck Clam

Giant Pacific Oyster

Giant Pacific Oyster

Chitons

Black leather Chiton

Black leather Chiton

– Mossy Chiton, Black Leather Chiton, Gould’s Baby Chiton, Smooth Lepidozona and 

  Giant Gumboot Chiton

Crabs

Flattop Crab

Flattop Crab

– assorted Hermit Crabs, Purple Shore Crab, Flattop Crab,  Flat Porcelain Crab and

  Black-clawed crab

Sea Cucumbers

California Sea Cucumber

California Sea Cucumber

– California Sea Cucumber and Orange Sea Cucumber

Eggs

Moon Snail eggs

Moon Snail eggs

– Moon Snail and assorted snails

Fish

Tidepool Sculpins

Tidepool Sculpins

– Tidepool Sculpin, Crescent Gunnel,  Northern Clingfish

Isopods

Rockweed Isopod

Rockweed Isopod

– Rockweed Isopod

Limpets

Pacific Plate Limpet

Pacific Plate Limpet

– Pacific Plate Limpet, Fingered Limpet, Mask Limpet, Ribbed Limpet, Keyhole Limpet

Mussels

Blue Mussel

Blue Mussel

– Blue Mussel

Nudibranch

Sea Lemon Nudibranch

Sea Lemon Nudibranch

– Sea Lemon and Barnacle-Eating Nudibranch

Seaweeds

Sea Asparagus

Sea Asparagus

– Rock Weed, Eelgrass, Bull Kelp (washed up), Sea Asparagus , Short Sea Lettuce,

   Turkish Towel, and Stringy Sea Lettuce

Snails

Wrinkled Dogwinkle

Wrinkled Dogwinkle

– Moon Snail, Frilled Dogwinkle, Striped Dogwinkle, Sitka Periwinkle and

  Checkered Periwinkle

Birds

Black Oystercatcher

Black Oystercatcher

– Bald eagle, Oystercatcher, Shore birds, Kildeer, Ducks, Cormorants, Sea Gulls

Mammals

Stellar Sea Lion

Stellar Sea Lion

– Harbor Seals, Steller Sea Lions, Elephant Seals, River Otters,  Mink

Shrimp

Sitka Shrimp

Sitka Shrimp

– Sitka Shrimp

Sea Stars

Grey Brittle Star

Grey Brittle Star

– Ocre Star, Six-Rayed Sea Star, Grey Brittle Star, Blood Star and Sunflower Star

Urchins

Green Sea Urchin

Green Sea Urchin

– Red Sea Urchin and Green Sea Urchin

Worms

Tapered Flatworm

Tapered Flatworm

– Tube Worm, Flat Worms, Tapered Flatworm, Intertidal Flatworm, Sand Worm,

   Green-Yellow Ribbon Worm, Spaghetti Worm, and Eighteen-Scaled Worm