Subtidal Organisms - Exposed Sand Beach

Zuma Beach Subtidal Patterns Based on the published findings of Dr. Jim Morin and his team from the UCLA Dept of Biology.

1- Life underwater at Zuma Beach.

2- Life in Dume Canyon.

OUR LOCATION:

34O 01.15’ N 118O 49.73’ W

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3 ZONES of LIFE at ZUMA BEACH UNDERWATER

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Underwater there are 3 zones of life at Zuma Beach.

SHOREWARD ZONE

Underwater there are 3 zones of life at Zuma Beach.

SHOREWARD ZONE $AND DOLLAR ZONE

Underwater there are 3 zones of life at Zuma Beach.

SHOREWARD ZONE $AND DOLLAR ZONE SEAWARD ZONE

Underwater there are 3 zones of life at Zuma Beach.

Shoreward zone

The shoreward zone begins underwater at the low tide line and runs out to sea about 55 m to an ocean depth of 6.4 m.

Zone 1 - Shallow Shoreward Zone. (d = 0 to 6.4 m) Characterized by low diversity, low abundance, low biomass, strong wave action and shifting sands.

Zone 1 - Shallow Shoreward Zone. (d = 0 to 6.4 m) Characterized by low diversity, low abundance, low biomass, strong wave action and shifting sands.

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Blepharipoda occidentalis Spiny Sand Crab

Tivela stultorem Pismo Clam

Olivella biplicata Purple olive snail.

Renilla kollikeri Sea Pansy (whole colony)

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Blepharipoda occidentalis Spiny Sand Crab Feeds on plankton part of the time, but also consumes young Emerita analoga sand crabs.

Zone 1 - Shallow Shoreward Zone. (d = 0 to 6.4 m) Characterized by low diversity, low abundance, low biomass, strong wave action and shifting sands.

Sea Pansy polyp (magnified)

Uses its stinging tentacles to stun and consume zooplankton.

This species is very Renilla kollikeri bioluminescent.

Sea Pansy (whole colony)

Zone 1 - Shallow Shoreward Zone. (d = 0 to 6.4 m) Characterized by low diversity, low abundance, low biomass, strong wave action and shifting sands.

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Tivela stultorem Pismo Clam

Pismo clams bury in the sand just below the bottom. Two holes in the sand are really the end of the siphons which pump water in and out of the clam constantly.

Tivela, like all bivalve mollusks, is a suspension feeder.

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Zone 1 - Shallow Shoreward Zone. (d = 0 to 6.4 m) Characterized by low diversity, low abundance, low biomass, strong wave action and shifting sands.

Olivella biplicata Purple olive snail.

The Chumash indians made necklace beads using Olivella shells.

Olivella plows its way through the sand. It feeds on deposits of detritus and algae in the sand.

$and Dollar zone

The $and dollar zone begins at a depth of depth of 6.4 m and runs about 100 m offshore to a depth of 9 meters.

Zone 2 - $and Dollar Middle Zone. (d = 6.4 m to 9.1m) Characterized by a high diversity of $and dollar$, high abundance, highest biomass of all 3 zones, moderate surge and little sand fluctuation.

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Zone 2 - $and Dollar Middle Zone. (d = 6.4 m to 9.1m) Characterized by a high diversity of $and dollar$, high abundance, highest biomass of all 3 zones, moderate surge and little sand fluctuation.

Dendraster excentricus, the Western $and Dollar, is an echinoderm related to spiny sea urchins.

The $and dollar bed parallels the shore from Pt. Dume to Broad Beach.

Dendraster is found on edge, like a wheel, in the sand.

mouth

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Zone 2 - $and Dollar Middle Zone. (d = 6.4 m to 9.1m) Characterized by a high diversity of $and dollar$, high abundance, highest biomass of all 3 zones, moderate surge and little sand fluctuation.

Dendraster excentricus, standing erect in the sands of Zone 2, points its mouth into the current and captures plankton. The food travels in grooves to the central mouth.

Direction of current mouth

In the summer, when the $and dollar bed contracts, population densities of 1,200 Dendraster per m2 have been counted !

Dendraster bed, aboral view.

This amazing density of Dendraster provides a “trap� for detritus and also gives shelter to numerous smaller animals that hide in between the dollar$.

Zone 2 - $and Dollar Middle Zone.

Other organisms found living in the $and Dollar zone: Spider crab Loxorhynchus grandis

Pink sea star Pisaster brevispinatus

Purple crab Randalia ornata

Parchment tube worm Diopatra ornata (also found in Zone 3)

Zone 2 - $and Dollar Middle Zone.

Other organisms found living in the $and Dollar zone: Spider crab Loxorhynchus grandis

The largest crab in southern California, Loxorhynchus scavenges the bottom around the $and Dollar$ feeding on sessile inverts and algae debris.

1 meter

Zone 2 - $and Dollar Middle Zone.

Other organisms found living in the $and Dollar zone: 4 cm

The Purple crab, Randalia ornata, is much smaller than Loxorhynchus, about 4 cm wide. This species scavenges the bottom for smaller pieces of animal and plant material. It is a reddish-purple color with white mottled areas.

Zone 2 - $and Dollar Middle Zone.

Other organisms found living in the $and Dollar zone: Up to 50 cm

Pink sea star Pisaster brevispinatus

The pink sea star, Pisaster brevispinatus is a carnivorous scavenger. It is found near the outer edge of the $and dollar bed and is one of the few animals to actually eat Dendraster excentricus.

Seaward zone

The Seaward zone begins at a depth of depth of 9 m and runs about 220 m offshore to a depth of 13.1 m.

Zone 3 - Seaward Zone. (d = 9.1 m to 13.1 m) A stable zone with little surge or sand movement. Greatest diversity, (mostly of motile predators) few numbers of individuals and low total biomass.

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Zone 3 - Seaward Zone. (d = 9.1 m to 13.1 m) A stable zone with little surge or sand movement. Greatest diversity, (mostly of motile predators) few numbers of individuals and low total biomass.

Megasurcula carpenteriana

Astropecten spp.

Stylatula elongata

Heterocrypta occidentalis

Diopatra ornata

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Zone 3 - Seaward Zone. (d = 9.1 m to 13.1 m) A stable zone with little surge or sand movement. Greatest diversity, (mostly of motile predators) few numbers of individuals and low total biomass.

Detailed view of bottom.

Astropecten (there are at least 2 species here) patrols the seaward zone

and is found living at these depths along most sandy subtidal regions of southern California. The spines are along the margins of the sea star.

The podia underneath are shaped like shovels to help this sand star dig its way across the sand. It is a scavenger.

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Zone 3 - Seaward Zone. (d = 9.1 m to 13.1 m) A stable zone with little surge or sand movement. Greatest diversity, (mostly of motile predators) few numbers of individuals and low total biomass.

20 cm

Stylatula elongata

the Sea Pen

Stylatula lives in a bulb under the sand and extends its body into the water to sting zooplankton. Like Renilla, it is also a very bioluminescent animal colony.

7 cm Diopatra is a tubedwelling polychaete worm. Unlike most tubeworms that feed on plankton, this species has jaws and will extend out of its Diopatra home in the tube to ornata attack and kill small the Parchment animals.

Tube Worm

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Zone 3 - Seaward Zone. (d = 9.1 m to 13.1 m) A stable zone with little surge or sand movement. Greatest diversity, (mostly of motile predators) few numbers of individuals and low total biomass.

Megasurcula carpenteriana, Carpenter’s Turret snail, is an unusual carnivorous gastropod mollusk. It has a long proboscis that can be used to drill into other organisms and eat them.

8 cm

Heterocrypta occidentalis, the socalled “elbow crab,� scavenges along the outer edge of the $and dollars.

6 cm

end of presentation