The California sea hare, (Angeloni, et al., 2003), is found along the California coast from Humboldt Bay in northern California to the Gulf of California, Baja California, Mexico.
The eggs are fertilized within a sperm storage cavity also known as the seminal receptacle before they are laid in bright pink, long gelatinous strings. These noodle-like egg masses may hold millions of embryos. Eggs usually hatch after approximately twelve days, releasing planktonic larvae. Mating occurs during spring and summer. Egg laying is initiated by copulation. ("The Rosenstiel School Of Marine and Atmospheric Science", 2009)
After an individual ("The Rosenstiel School Of Marine and Atmospheric Science", 2009)lays its egg mass, which likely contains provisioning, there is no further investment in the offspring.
Sea hares’ lifespans are usually fairly short as they typically live only a year. Most sea hares perish after reproduction. However, because water temperatures delay reproduction, cooler waters can somewhat lengthen lifespan. ("California Brown Sea Hare", 2014)
One of the more notable behavioral aspects noticed in sea hares is their ability to release a deep purple ink from within the parapodia when threatened. The deep purple color is derived from pigments within the red algae in their diet. The ink has been shown to be distasteful and acts as a defense mechanism to ward off predators. In order to avoid being attacked, sea slugs are mainly active at night. Sea hares give a cautionary avoidance response when in contact with certain sea stars and predaceous opisthobranchs. This response consists of withdrawing the head rapidly and engaging in an escape response. (Angeloni, et al., 2003; "Opisthobranch parasites - the copepod Ismaila", 2010; Nusnbaum and Derby, 2010)
has no specific home range.
Sea hares congregate to mate, and thus they perceive conspecifics via tactile and chemical cues. These slugs have photoreceptors that detect variances in the intensity of white light. However, they are less able to identify red wavelengths. Overall, sea slugs respond more to chemical changes in seawater. A sensing structure located near the gills called the osphradium detects dissolved chemicals and is the major organ of olfaction. (Angeloni, et al., 2003)
Laurencia pacifica, Plocamium pacificum and Ceramium spp.) as well as sea lettuce (Ulva spp.) and eelgrass (Zostera marina) from within tidepools in the middle intertidal zone. Aplysia uses its toothed radula to graze attached algae. After the material has been temporarily stored in the esophagus, it is then passed through a muscular stomach lined with pyramidal teeth which further grind up the food matter. The food is then mixed with various digestive fluids and wastes are excreted out the anus located near the parapodia. The larvae obtain nourishment by consuming phytoplankton. (Angeloni, et al., 2003; Winkler and Dawson, 1963)is a herbivore and primarily feeds on several kinds of red algae (
Due to their lack of an outer calcareous shell, sea hares utilize cryptic coloration, nocturnal behaviors, and ink release as defense mechanisms. Sea hares are also distasteful to many predators due to chemicals known as secondary metabolites which they create from chemicals obtained from their algal diet. This chemical adaptation also makes sea hare tissue somewhat toxic to certain animals and fairly effective against most predators. It has been discovered that the mucus covering the mantle also acts a deterrent against predatory crustaceans and some fish. Two of the main predators are the giant green sea anemone, Anthropleura xanthogrammica, and the ophistobranch slug, Navanax inermis. (Angeloni, et al., 2003; "Opisthobranch parasites - the copepod Ismaila", 2010)
There are no known adverse effects ofon humans.
Although there is no current management or conservation plan for this species, individuals are protected if they occur within the boundaries of marine protected areas.
The purple ink released by these animals smells pleasantly of cedar (P. Detwiler, pers. comm.).
Samantha Dice (author), San Diego Mesa College, Paul Detwiler (editor), San Diego Mesa College, Angela Miner (editor), Animal Diversity Web Staff.
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.
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.
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.
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
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.
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
union of egg and spermatozoan
An animal that eats mainly plants or parts of plants.
ovulation is stimulated by the act of copulation (does not occur spontaneously)
fertilization takes place within the female's body
the area of shoreline influenced mainly by the tides, between the highest and lowest reaches of the tide. An aquatic habitat.
seaweed. Algae that are large and photosynthetic.
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.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
active during the night
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
chemicals released into air or water that are detected by and responded to by other animals of the same species
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal which has a substance capable of killing, injuring, or impairing other animals through its chemical action (for example, the skin of poison dart frogs).
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
mainly lives in oceans, seas, or other bodies of salt water.
breeding is confined to a particular season
remains in the same area
offspring are all produced in a single group (litter, clutch, etc.), after which the parent usually dies. Semelparous organisms often only live through a single season/year (or other periodic change in conditions) but may live for many seasons. In both cases reproduction occurs as a single investment of energy in offspring, with no future chance for investment in reproduction.
reproduction that includes combining the genetic contribution of two individuals, a male and a female
uses touch to communicate
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).
uses sight to communicate
Aquarium of the Pacific. 2014. "California Brown Sea Hare" (On-line). Aquarium of the Pacific. Accessed February 17, 2014 at http://www.aquariumofpacific.org/onlinelearningcenter/species/california_brown_sea_hare.
Australian Museum. 2010. "Opisthobranch parasites - the copepod Ismaila" (On-line). The Sea Slug Forum. Accessed May 09, 2014 at http://www.seaslugforum.net/find/ismaila.
Universty of Miami. 2009. "The Rosenstiel School Of Marine and Atmospheric Science" (On-line). The National Resource for Aplysia. Accessed April 01, 2014 at https://cc1.rsmas.miami.edu/slugs/.
Angeloni, L., J. Bradbury, R. Burton. 2003. Multiple mating, paternity, and body size in a simultaneous hermaphrodite, Behavior Ecology, 14/4: 554-560..
Audesirk, T. 1979. A field study of growth and reproduction in The Biological Bulletin, 157/3: 407-421. Accessed February 18, 2014 at http://www.biolbull.org/content/157/3/407.full.pdf..
Krauhs, J., J. Long, P. Baur. 1979. Spores of a New Microsporidan Species Parasitizing Molluscan Neurons. The Journal of Protozoology, 26/1: 43-46.
Macginitie, G. 1934. "The egg laying activities of the sea hare Tethys californicus" (On-line). Accessed February 16, 2014 at http://www.biolbull.org/content/67/2/300.full.pdf.
Morris, R., D. Abbott, H. Eugene, R. Beeman, G. Williams. 1980. Intertidal Invertebrates of California. Stanford, CA: Stanford University Press.
Nusnbaum, M., C. Derby. 2010. Effects of Sea Hare Ink Secretion and Its Escapin-Generated Components on a Variety of Predatory Fishes. The Biological Bulletin, 218: 282-292. Accessed February 17, 2014 at http://www.biolbull.org/content/218/3/282.full.pdf+html.
Pawlik, J. 1989. Larvae of the sea hare Marine Ecology Progress Series, 51: 195-199. Accessed February 17, 2014 at http://people.uncw.edu/pawlikj/1989MEPSPaw.pdf.settle and metamorphose on an assortment of macroalgal species.
Winkler, L., E. Dawson. 1963. Observations and Experiments on the Food Habits of California Sea Hares of the Genus Aplysia. Pacific Science, 17: 102-105. Accessed February 17, 2014 at http://scholarspace.manoa.hawaii.edu/bitstream/handle/10125/4930/vol17n1-102-105.pdf?sequence=1.