Species – Invertebrates

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Learn more about the invertebrates monitored by the LiMPETS program. The list below includes:

  • 17 core taxa that are monitored at as many sites as possible
  • 5 other taxa (denoted with *) that are monitored at only one or two sites

Go to Datasheets and Forms to find out which species are monitored at your LiMPETS site of interest.

Aggregating Anemone

Aggregating Anemone (Anthopleura elegantissima)

Aggregating Anemone
Description

Small (2-5 cm) greenish-colored body, often with pink-tipped tentacles; large rounded tubercles arranged in vertical rows on column, often covered in sand and shells; radiating lines in oral disc; can form dense aggregations.

Distribution
Alaska to Baja California.
Habitat
Semiprotected rocky shores of bays and rocky coasts; abundant on rocks, in crevices or in tidepools in mid zone.
Diet
Predator, eating copepods, isopods, amphipods, and other small animals that come in contact with the tentacles. Also possess symbiotic algae within their tissues that provide supplimental nourishment and oxygen.
Fun Fact

These anemones can reproduce asexually or sexually; asexually by producing clones of themselves by longitudinal fission. All individuals in a group are members of a single clone, and are genetically identical to one another. Each clone is either male or female and all members produce either sperm or eggs.

Reason for Monitoring

These anemones can reproduce asexually or sexually; asexually by producing clones of themselves by longitudinal fission. All individuals in a group are members of a single clone, and are genetically identical to one another. Each clone is either male or female and all members produce either sperm or eggs.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Black Abalone

Black Abalone (Haliotis cracherodii)

Black Abalone
Description

The low, shield-like, smooth shell of this abalone is dark blue, dark green, or almost black in color. Shell can reach lengths of 20 cm or more and contains a line of holes used for ventilation. Tentacles are black.

Distribution
Mendocino County, California to Baja California; rare north of San Francisco.
Habitat
Common under rocks and in crevices, from the high intertidal to 6 meters depth. This species occurs higher in the intertidal than any other California abalone.
Diet
Herbivore, eating diatoms films, coralline algae, and loose pieces of algae brought in by waves.
Fun Fact

Natural predators of the abalone include octopuses, whelks, sea stars, fish, sea otters, and humans.

Reason for Monitoring

Abalone populations once occurred at a density of 60 to 80 individuals per square meter and dominated the intertidal in southern California. This species has experienced population decline due to overfishing, poaching, and disease (i.e., withering syndrome) throughout its range and has gone locally extinct in most locations south of Point Conception.

 

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

National Geographic News

UCSC’s Pacific Coast Rocky Intertidal Monitoring: Haliotis cracherodii (Black Abalone)

Chitons

Chitons (Mopalia spp./ Nuttallina spp./ Tonicella spp./others)

Chitons
Description

Chitons are a basal group of mollusks. They are oval in shape and have 8 separate, overlapping calcareous plates. The plates are embedded in a tough muscular girdle. They can be many different colors and can be easily overlooked because they are often small and well camouflaged.

 

Distribution
Alaska to Baja California.
Habitat
Fairly common on intertidal rocky shores; many are nocturnal and remain hidden under rocks in the daytime.
Diet
Chitons scrape algal films off the rocks with their radula; also feed on other algae such as stunted Turkish towel, scouring pad alga, coralline algae, and green-pin cushion alga.
Fun Fact

Like snails and limpets, chitons have a long tongue-like radula used for feeding. The radula has rows of strong, iron-capped teeth that scrape algae off of the rocks. Although they have no real “head” they have many tiny eyes in their shells.

Reason for Monitoring

Important grazers of algae in the intertidal.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Common Acorn Barnacles

Common Acorn Barnacles (Balanus glandula/ Chthamalus dalli/fissus)

Common Acorn Barnacles
Description

Balanus glandula is moderate in size (~2 cm), white with a diamond-shaped operculum and more heavily ribbed walls. Chthamalus dalli/fissus is smaller (<1 cm), brownish with an oval shaped operculum, and smoother walls.

Distribution
Alaska to Baja California. Balanus glandula has been introduced to the shores of Argentina in the past 30 years, and has become an invasive species there.
Habitat
Found along the open coast and in bays. Balanus glandula is common in mid to low intertidal on mussels and rocks. Chthamalus dalli/fissus is common in the high to mid intertidal.
Diet
Plankton. Barnacles filter plankton from the water using their feathery, segmented legs.
Fun Fact

As adults, barnacles are hermaphrodites. They fertilize one another internally by means of a long penis. The eggs are brooded by the parent and released as nauplius larvae.

 

Reason for Monitoring

Competitors for space in the high and mid zone. Major prey for many intertidal species. Susceptible to high mortality from oil spills because oil can stick to high intertidal habitat.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Chthamalus/Balanus (Acorn Barnalces)

 

Giant Green Anemone

Giant Green Anemone (Anthopleura xanthogrammica)

Giant Green Anemone
Description

Large, solitary anemone up to 25 cm in diameter (10 inches), same size as sunburst anemone or larger; olive-green to bluish green disc without radiating lines; small irregular tubercles arranged haphazardly on column gives this beautiful creature a velvet-like texture.

Distribution
Alaska to northern Baja California.
Habitat
Usually in pools within or below mussel beds, low intertidal to subtidal; found on exposed rocky shores, in open bays and harbors.
Diet
Mainly detached mussels, crabs, sea urchins and small fishes. Also possess symbiotic algae within their tissues that provide supplimental nourishment and oxygen. The striking bluish-green color is caused by pigments produced by the animals themselves, not the algae, which in California are golden brown in color (farther north some specimens have grass-green algae in their tissues).
Fun Fact

Stinging cells called cnidocytes are located within the tentacles of all anemones. These cells help the anemone to paralyze its prey; however, stinging cells of California anemones do not harm humans when touched, but those of some tropical species cause painful stings.

Reason for Monitoring

This is a northern species. Though it occurs from Alaska to northern Baja California, it is restricted to upwelling areas in the southern part of its range. Distribution of this species may shift farther north if global warming continues. Major space competitor and predator, associated with mussels.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Hermit Crabs

Hermit Crabs (Pagurus spp.)

Hermit Crabs
Description

Rocky intertidal hermit crabs in California are represented by the family Paguridae. They live in the abandoned shells of snails to protect their soft abdomens. Carapace grows to approximately 2 cm in length. P. hirsutiusculus, abundant in the mid zone, has white bands on walking legs, dark antennae with fine white bands, and a dark orange-brown body. P. samuelis is the most abundant hermit crab in the high zone of central and southern California. It has a hairy carapace and legs, blue bands on walking legs, and red antennae.

 

Distribution
Varies with species.
Habitat
Common in tidepools on rocky shores; P. hirsutiusculus is usually found in the mid to low intertidal; P. samuelis is typically found in the high to mid intertidal but also subtidally in giant kelp holdfasts.
Diet
Important scavengers of dead plant and animal matter.
Fun Fact

Hermit crabs can be choosey about the shells they live in.
P. hirsutiusculus
 prefers the shells of olive snails while P. samuelisprefers the shells of turban snails.

Reason for Monitoring

Important scavengers of dead plant and animal matter. Sensitive to pollution. Fun to count.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Honeycomb Tube Worm

Honeycomb Tube Worm (Phragmatopoma californica)

Honeycomb Tube Worm
Description

These marine solitary, polychaete worms form large aggregations of cemented sand-grain tubes. Tubes form masses up to 2 m in length and are positioned in a honeycomb arrangement, each tube with a flared rim. Though the group of tubes looks like a colony, each tube is the result of one individual worm settling near other worms and building its home. These worms are up to 5 cm in length and bear a crown of lavender tentacles.

Distribution
Range from central California to Ensenada, Baja California.
Habitat
Common mid to low intertidal; often overgrowing mussels, barnacles, and algae; solitary tubes meander on rocks in high mid zone.
Diet
Plankton and detritus.
Fun Fact

This worms captures sand with its tentacles and transports the grains to an organ behind the mouth. Liquid cement is added to the sand for the construction of the walls of its tube.

Reason for Monitoring

Major space competitor, mid zone indicator.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Leaf (or Gooseneck) Barnacle

Leaf (or Gooseneck) Barnacle (Pollicipes polymerus)

Leaf (or Gooseneck) Barnacle
Description

Barnacle on dark, fleshy stalk; up to 8 cm in length; the top is covered with more than 5 white plates and surrounded by scales.

Distribution
British Columbia to Baja California.
Habitat
Form aggregations on rocks and among mussels; mid intertidal zone on wave-exposed rocky shores.
Diet
Filter feeds on particles of dead, decaying plants and animals in the backwash of waves. They often orient themselves to face the current and are therefore mostly seen facing the same direction.
Fun Fact

These barnacles are a main food source for Glaucous-winged Gulls. In Europe, humans harvest and eat another species of leaf barnacles.

Reason for Monitoring

Mid zone indicator; major space competitor with mussels.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Pollicipes (Goose Barnacle)

Limpets

Limpets (Lottia spp.)

Limpets
Description

Limpets are a group of gastropod mollusks with one uncoiled cone-shaped or flattened shell. Their muscular foot helps them cling to rocks. There are a handful ofLottia species that inhabit the rocky intertidal of California: the shield limpet (L. pelta), ribbed limpet (L. austrodigitalis/digitalis), rough limpet (L. scabra), file limpet (L. limatula), owl limpet (L. gigantea), and others. These limpets range from 12 mm to 10 cm in size. Shell color varies, though most are brownish and mottled and are well camouflaged.

Distribution
Varies by species. The Family Lottidae has worldwide distribution, although the greatest diversity is on the west coast of North America.
Habitat
Most live intertidally, although some live on sea grasses and kelps. Many are common on vertical rock faces in the high intertidal and splash zone.
Diet
Important grazers of algae, especially microscopic films of algae and diatoms, on rocky surfaces.
Fun Fact

Limpets often remain motionless during low tide during the day, but move about and forage at night, mainly during low tide. Some limpets will return after grazing to their own unique resting spot on the rock known as a “home site.” On soft rock, they chew out a depression in which their shells just fit, but on hard rock their shell grows to fit the rock.

Reason for Monitoring

Major grazers and prey for shorebirds.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Stanford’s SeaNet: Rocky Shore Limpets

Ochre Sea Star

Ochre Sea Star (Pisaster ochraceus)

Ochre Sea Star
Description

Sea star typically has 5 arms, but rarely has from 4-7; aboral surface with many small white spines; average length is 14 cm; color yellow/orange or deep brown/purple.

Distribution
Range Alaska to Santa Barbara, CA.
Habitat
Common in the middle and low intertidal; juveniles found in crevices and under rocks.
Diet
These sea stars can evert their stomachs and insert them into prey such as mussels, barnacles and snails.
Fun Fact

Some prey can detect a scent from the ochre star and move away from the predator. This star has few predators including sea otters, gulls, and humans (for ornaments).

Reason for Monitoring

Important predators, vulnerable to parasitic castration, and overcollecting by humans.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Owl Limpet

Owl Limpet (Lottia gigantea)

Owl Limpet
Description

This is the largest limpet in North America, reaching sizes up to 8 cm (3.5 inches) in length. The shell is oval and low in profile with the apex (highest point of the shell) positioned far forward. Shell surface often rough with raised brown areas relative to white areas. Tentacles and side of foot gray.

Distribution
Neah Bay, Washington to Baja California.
Habitat
Found in the mid to high zone, on cliff faces and rocks of wave-exposed shores.
Diet
Grazes algal films off rocks with a hard radula.
Fun Fact

Owl limpets are hermaphrodites. They are born males and become females as they grow older and larger. The females have distinct grazing territories or “farms” that they clear by scraping rocks free of algae. This action creates space and promotes algal growth. Females are territorial and will dislodge small mussels, limpets and anemones from their territories by bulldozing them off the rock with the edge of their shell.

Reason for Monitoring

Humans eat owl limpets and preferentially take the largest limpets in a population for consumption. As a result, populations may become dominated by smaller males, skewing the gender ratio and decreasing reproduction.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Lottia gigantea (Owl Limpet)

Pink Acorn Barnacle

Pink Acorn Barnacle (Tetraclita rubescens)

Pink Acorn Barnacle
Description

Pink acorn barnacles are large (3-5 cm), ribbed, and reddish-pink in color. They are usually found growing as solitary individuals rather than in groups.

Distribution
Mendocino County to southern Baja California. This species has expanded its northern range limit by several hundreds of kilometres from San Francisco, CA, USA, since the 1970s.
Habitat
Common, but scattered, in mid-low intertidal zones; often found amongst mussels.
Diet
Plankton
Fun Fact

This barnacle is an effective competitor for space in the low intertidal zone, and individuals may grow to a size large enough to exempt them from predation by many gastropods and sea stars. Some individuals may live as long as 10-15 years.

Reason for Monitoring

These barnacles are a southern species nearing their northern limit in the Monterey Bay National Marine Sanctuary (MBNMS). Their abundance in the MBNMS is expected to increase if global warming continues. This species might be sensitive to sewage pollution.

References

Dawson, M. N., Groberg, R. K., Stuart, Y. E. and Sanford, E. 2010. Population genetic analysis of a recent range expansion: mechanisms regulating the poleward range limit in the volcano barnacle Tetraclita rubescens. Molecular Ecology 19: 1585–1605. doi: 10.1111/j.1365-294X.2010.04588.x

Littler, M.M. and Murray and S.N. Murray 1975. Impact of sewage on the distribution, abundance, and community structure of rocky intertidal macro-organisms. Marine Biology 30:277-291.

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Tetraclita (Pink Barnacle)

Purple Sea Urchin

Purple Sea Urchin (Strongylocentrotus purpuratus)

Purple Sea Urchin
Description

The body and spines of this echinoderm are typically bright purple; juveniles are green; average body size is 5 cm in diameter; tube feet allow animals to cling to rocks.

Distribution
Alaska to Baja California.
Habitat
Common in lower intertidal zone and near pilings with strong wave action; commonly inhabit rounded burrows or depressions in rocks formed by the spines and the grinding teeth of the urchin.
Diet
A variety of brown and red algae, but they prefer giant kelp.
Fun Fact

Urchins can regenerate broken spines. This is the first species of sea urchin that has had its complete genome sequenced; it is a model animal for the study of development.

Reason for Monitoring

This species is harvested for food in California. In 2000, 20 million lbs of sea urchins were harvested, primarily for markets in Japan.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Stanford’s SeaNet: Phylum Echinodermata

Sea Mussel

Sea Mussel (Mytilus californianus)

Sea Mussel
Description

Bivalve mollusk; shell up to 20 cm in length, black and bluish in color with coarse ribs.

Distribution
Aleutian Islands to Baja California.
Habitat
Dominant member of mid-intertidal zone; found in surf zone on rocks and wharf pilings.
Diet
Plankton
Fun Fact

Mussels are attached to hard substrate by secreting byssal threads at the base of the foot. Mussel beds provide important refuge and habitat for a variety of invertebrates and algae.

Reason for Monitoring

Competitive dominant; major space occupier in mid zone. Harvested extensively by humans for food (great steamed and dipped in garlic butter!), but can contain deadly poison.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

UCSC’s Pacific Rocky Intertidal Monitoring: Mytilus (California mussel)

Sunburst Anemone

Sunburst Anemone (Anthopleura sola)

Sunburst Anemone
Description

This anemone is distinguished by the sunburst pattern of radiating lines on oral disk; most are 10-15 cm (4-6 inches) in crown diameter, but can reach up to 25 cm (10 inches) in diameter. Tentacles usually with white blotches, rarely pink-tipped; can be confused with giant green anemones because they are similar in size, but are distinguished by lines on disc and tubercles in rows on column. More difficult to distinguish from aggregating anemone as main difference is mode of growth: clonal versus solitary; recent genetic studies revealed that the two are separate species that do not interbreed.

Distribution
Northern central California to central Baja California.
Habitat
Often abundant on rocks surrounded by sand, mainly in lower mid zone extending well into the subtidal.
Diet
Prey mainly on small crustaceans and other animals in the plankton, but also take dislodged mussels and other intertidal animals. Also possess symbiotic algae within their tissues that provide supplimental nourishment and oxygen.
Fun Fact

Closely related to the aggregating anemone, this species was given its own name only recently. Up until then it was known as a form of aggregating anemone that lived in the low intertidal in southern California and did not clone, remaining solitary. There is another solitary sea anemone that looks similar, the giant greet anemone, that lives intertidally in the cooler waters of central and northern California but it lacks the conspicuous radiating lines on the oral disk.

 

Reason for Monitoring

This is a southern species near its northern limit in central California. Their abundance in central and northern California is expected to increase if global warming continues. Major space competitor and predator.

References

Biological Sciences: Santa Barbara City College

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Pearse V. and Francis L. 2000. Anthopleura sola, new species, solitary sibling species to the aggregating sea anemone, A. elegantissima (Cnidaria: Anthozoa: Actiniaria: Actiniidae). Proc Biol Soc Washington 113: 596-608.

Turban Snails

Turban Snails (Chlorostoma brunnea/funebralis)

Turban Snails
Description

Shell is round, shaped like a turban, not pointed at the apex; can be dark purple, black, orange, or brown in color; usually to 3 cm in diameter; often aggregates in groups.

Distribution
C. brunnea range is from Oregon to Santa Barbara (Channel Islands). C. funebralis range is from Vancouver Island to Central Baja California.
Habitat
Turban snails are some of the best known snails along the coast; black turbans (C. funebralis) are very abundant in tidepools and on rocks in the high and mid tide zone of the rocky intertidal. Brown turbans (C. brunnea) are common in low intertidal zone and shallow subtidal rocky shores.
Diet
Herbivore that eats microscopic films and macroscopic algae.
Fun Fact

Turban snails are preyed upon by sea otters, rock crabs and the ochre sea star; also collected by humans for food.

Reason for Monitoring

These are major grazers of algae in the intertidal. They are also harvested by people for food.

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

Whelks

Whelks (Acanthinucella spp./Nucella spp./others)

Whelks
Description

Whelks are a group of predatory snails. The shells can be lots of different colors; black, grey, orange, purple with stripes, gray with stripes; up to about 4 cm in length. Note that both ends of whelk shells are pointed.

Distribution
Varies with species.
Habitat
High and middle intertidal zones mostly; on rocks experiencing some wave action; unicorn snails (Acanthinucella spp.) and dogwinkles (Nucella spp.) are often found in mussel beds and among barnacles.
Diet
Feeds primarily on mussels, barnacles, limpets and herbivorous snails such as turban snails and periwinkles; holes are drilled in the shells of prey by means of the radula and an accessory boring organ located on the sole of the foot which softens the shell.
Fun Fact

Unicorn snails and dogwinkles spawn sporadically throughout the year in California most actively from November to March. Females deposit their eggs in yellow vase shaped capsules (as many as 300 capsules per cluster with average of 500 eggs per capsule).

Reason for Monitoring

These are major predators in the intertidal.

 

References

Morris, R.H., D.P. Abbott, and E.C. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California.

We also monitor:

  • Loose sand
  • Tar (petroleum)
  • Bare rock