Geographic Range
Distribution of the green abalone,
Haliotis fulgens
, in the Pacific Ocean ranges from Point Conception in Santa Barbara, California to
the mid-coast of Baja California, Mexico.
- Biogeographic Regions
- pacific ocean
Habitat
The green abalone resides in shallow water, in depths from nine meters to eighteen
meters. The abalone is found in rock crevices, and other protected cavities in the
inter-tidal zones.
- Habitat Regions
- temperate
- saltwater or marine
- Other Habitat Features
- intertidal or littoral
Physical Description
The green abalone has a flattened univalve shell scored with wavy lines; five to seven
raised holes lie along the shell margin. These holes are used for excurrent water
flow in the process of respiration. Its shell length approaches 13 cm, and ranges
in color from dark shades of maroon to brown. The inside of the shell is coated with
nacre of a lustrous blue-green color. A ruffle of tissue (called the epipodium) lines
the edge of the wide, muscular foot which the animal uses to crawl over hard substrata.
The foot is cream and brown in color, with tubercles along the edges.
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Development
Haliotis fulgens
passes through several life stages. First the egg is fertilized, and hatches after
20 to 30 days. The egg hatches into a trochophore larva, a free-swimming, ciliated
planktonic stage. This develops into the next stage, a free-swimming veliger larva.
The veliger eventually sinks to the ocean floor, and becomes a sedentary juvenile.
Eventually, juveniles develop into reproductive adults.
- Development - Life Cycle
- metamorphosis
Reproduction
The green abalone reproduces by broadcast spawning, when both sexes release their
gametes into the water.
- Mating System
- polygynandrous (promiscuous)
The sex of the abalone can be determined by gonad color. The gonads are creamy white
in males, and green in females. During broadcast spawning, abalones release thousands
of sperm and eggs into the water column; thus, fertilization is external. There is
no seasonal reproductive cycle, however. Abalone release sperm or egg into the water
when they sense chemicals released during spawning by conspecifics. Spawning all at
once increases the odds of fertilization. Green abalone reach sexual maturity in 2
to 4 years.
- Key Reproductive Features
- iteroparous
- year-round breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- broadcast (group) spawning
- oviparous
There is no parental investment, as this species is a broadcast spawner.
Halitosis fulgens
releases its gametes, and the offspring are independent right from fertilization
on.
- Parental Investment
- no parental involvement
Lifespan/Longevity
Lifespan in the wild is estimated at 30 or more years. Mortality rate of young abalone
is high because of predation. Lifespan is also limited by the amount of available
food. Since the abalone’s diet mainly consists of drifting algae, its lifespan is
directly related to the persistence of kelp forests. Due to destruction of the kelp
beds via human activities and natural events, lifespan of
Haliotis fulgens
can be affected greatly.
Behavior
Haliotis fulgens
is a nocturnal, solitary creature that lives under rocks and in crevices in shallow
areas. It only moves around if algae is scarce; otherwise it is a sedentary, sessile
creature. It moves by crawling forward with its foot.
Home Range
Depending on food availability, abalone may stay in the same general area for months.
Abalone are known to compete with sea urchins for crevices in rocky substrates, but
they do not formally defend a territory.
Communication and Perception
Haliotis fulgens
uses its ruffled epipodium and tentacles along the inside of the foot to sense its
environment. Green abalones have a pair of eyes that detect light and shadow. Individuals
have olfactory senses to detect chemicals released by conspecifics that induce spawning.
The sperm and eggs of green abalone communicate (in a way) through chemicals. Dissolved
signal molecules cause sperm to accelerate towards an egg. Through the use of nuclear
magnetic resonance spectroscopy, the sperm attractant was found to be the amino acid
L-trytophan.
- Perception Channels
- visual
- tactile
- vibrations
- chemical
Food Habits
The diet of the green abalone mainly consists of drift and attached seaweed. Species
composition of the diet is directly related to the species abundance of algae in the
environment. The green abalone prefers fleshy red algae, and when food is scarce,
it is forced to forage. Like all
gastropods
, abalone use their toothed radula to scrape and ingest their food.
- Primary Diet
-
herbivore
- algivore
- Plant Foods
- algae
- macroalgae
Predation
The abalone is prey to any creature that can dislodge it from its rock. Predators include seals ( Phoca vitulina ), sea lions ( Zalophus californiaus ), sea otters ( Enhydra lutris ), fish, octopus ( Octopus bimaculoides ), and sea stars ( Asteroidea ). Humans are another threat to abalone as well.
The abalone's greatest natural predator is the sunflower star (
Pycnopodia helianthoides
). The sunflower star has no problem with the shell as it simply engulfs the entire
abalone and digests it. The only anti-predator defense that
Haliotis fulgens
has is by clamping down onto its rock or by crawling away from its predator.
- Anti-predator Adaptations
- cryptic
Ecosystem Roles
Haliotis fulgens
has a large role in the coastal ecosystem; as a herbivorous grazer it affects algal
recruitment onto bare surfaces via its radular scraping while feeding. As a juvenile,
the green abalone is easy prey for secondary consumers. The young seek refuge among
rocks and under the spine canopy of the red sea urchin
Strongylocentrotus franciscanus
. The sea urchins protect the abalone from predators in a commensal relationship.
In many cases, areas with low counts of sea urchins also show low counts of abalone.
However, as the abalone grow and reach adult size, they no longer need protection
from sea urchins, and competition for space begins, as both creatures prefer to inhabit
the same microhabitat of rock crevices.
The abalone's shell provides a hard substrate for epifaunal organisms to colonize,
including various benthic invertebrates such as worm snails, sponges, date mussels,
and bryozoans.
- Ecosystem Impact
- creates habitat
- red sea urchin, Strongylocentrotus franciscanus
- scaly worm snail, Serpulorbis squamigerus
- boring sponge, Cliona celata
- date mussel, Lithophaga attenuata
- bryozoan, Membranipora membranacea
Economic Importance for Humans: Positive
Haliotis fulgens
has economic importance to humans, as the foot is consumed. The shell can be used
for jewelry and decorative objects. Native Americans have used all parts of the abalone:
the meat as food, and the shell for tools, trade, and decorations. There has been
no commercial fishery since the dismantling of the commercial fishing companies that
hunted red abalone. Due to its economic importance to humans, the green abalone has
been raised in aquaculture since 1940, first at Stanford's Hopkins Marine Station
in Pacific Grove, California, and more recently at various coastal facilities within
southern California, primarily for the overseas restaurant trade.
- Positive Impacts
- food
- body parts are source of valuable material
Economic Importance for Humans: Negative
There are no known adverse effects of Haliotis fulgens on humans.
Conservation Status
Haliotis fulgens
has been a species of concern since 2004 because of over-harvesting. Population size
has been reduced because of over-fishing. The populations of green abalone unfortunately
are extremely low and there are many legal protections in effect. Some of these have
closed commercial and recreational fisheries, and an Abalone Recovery Management Plan
has been implemented through the state of California.
Additional Links
Contributors
Joshua Williams (author), San Diego Mesa College, Sarah Yesil (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Angela Miner (editor), Animal Diversity Web Staff.
- Pacific Ocean
-
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- benthic
-
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- intertidal or littoral
-
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- metamorphosis
-
A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- year-round breeding
-
breeding takes place throughout the year
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- tactile
-
uses touch to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- chemical
-
uses smells or other chemicals to communicate
- macroalgae
-
seaweed. Algae that are large and photosynthetic.
- cryptic
-
having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
References
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Riffell, J., P. Krug, R. Zimmer. 2002. Fertilization in the sea: the chemical identity of an abalone sperm attractant. The Journal of Experimental Biology , 205: 1439-1450. Accessed April 24, 2013 at http://instructional1.calstatela.edu/pkrug/lab/PDF/2002,%20Riffell%20et%20al.pdf .
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1996. "Abalone Growth and Development" (On-line). OceanLink. Accessed May 17, 2013 at http://oceanlink.info/Conservation/abalone/BHCAP/development.html .
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