Table of Contents
Overview
Distribution
Geographic Range
Sea Hares are marine animals that inhabit coastal regions thick with vegetation. This particular species, Aplysia californica, ranges from Northern California to Baja California.
Biogeographic Regions: pacific ocean (Native )
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Physical Description
Morphology
Physical Description
The California Black Sea Hare is probably the world's largest gastropod. It can weigh up to 35 pounds! It is typically about 16" long (41 cm) and 8" (20 cm) wide and high. Plump and soft, it has winglike flaps around the top of its head on both sides. Aplysia californica can be reddish, brownish, or greenish, spotted with white or dark circles and lines. The colors reflect the type and color of algae they are prone to eat. They feed with a pair of jaws and a grasping radula. On top of their head, two pairs of antennae are found: one low near the mouth and another behind the eyes. A foot used to help in locomotion extends a little farther than the entire length of the animal. The anterior tentacles are much larger and ear-like (thus its common name- the sea hare) than the second pair which are used more for smelling. They also possess winglike flaps called parapodia that are used for swimming. The mantle folds over and covers a thin, transparent, and flexible shell. In its wall are unicellular glands that secrete a purple dye when the animal is handled. The sea hare does possess a developed nervous and digestive system. In its digestive tract there is an alimentary canal in front of the stomach that ends in a crop lined with horny plates for better mastication before digestion of food.
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Ecology
Habitat
Habitat
Aplysia californica are marine animals that inhabit coastal regions thick with vegetation. This particular species ranges from Northern California to Baja California. They can usually be found crawling around the seaweed they use as a source of food. The younger generation live in the deeper waters where they are born while the adult generation lives in shallow, sheltered places with low tide.
- Borradaile, L., F. Potts. 1963. The Invertebrata: A Manual for the use of Students. Cambridge: Cambridge University Press.
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Trophic Strategy
Food Habits
Aplysia californica are herbivorous and feed on a variety of algae and eelgrass. Their pair of jaws and broad rasp-like radula help crop the seaweed they eat. The color of the particular animal matches the color of the algae or vegetation they feed on the most.
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Life History and Behavior
Reproduction
Reproduction
A. californica is hermaphroditic. Armed with a single aperture and duct for the sperm and ova, this species reproduces sexually. They travel to deeper waters to spawn around spring time. Once fertilized, their eggs are laid down in pink, gelatin-like stringed sacs coiled around seaweed or rocks.
- Borradaile, L., F. Potts. 1963. The Invertebrata: A Manual for the use of Students. Cambridge: Cambridge University Press.
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Evolution and Systematics
Functional Adaptations
Functional adaptation
The California sea hare inhibits microbial growth using escapin, a polypeptide.
"Escapin's antimicrobial effects, bacteriostasis and bactericidal, were determined using a combination of two assays: (1) incubation of bacteria on solid media followed by assessment of inhibition by direct observation of zones of inhibition or by turbidity measurements; and (2) incubation of bacteria in liquid media followed by counting viable colonies after growing on agar plates. Native escapin inhibited the growth of Gram-positive and Gram-negative bacteria, including marine bacteria (Vibrio harveyii and Staphylococcus aureus) and pathogenic bacteria (Staphylococcus aureus, Streptococcus pyogenes and Pseudomonas aeruginosa). Escapin also inhibited the growth of yeast and fungi, with different efficacies. Escapin's antimicrobial activity was concentration dependent and did not decrease when stored for more than 5 months at room temperature. Escapin was bacteriostatic and not bactericidal in minimal media (e.g. salt media) with glucose, yeast extract, and a mixture of 20 amino acids each at 50 µmol l-1, but was bactericidal in media enriched with Tryptone Peptone. Escapin was also strongly bactericidal in media with L-lysine at concentrations as low as 3 mmol l-1 and slightly bactericidal in 50 mmol l-1 L-arginine, but not in most other amino acids even at 50 mmol l-1. Escapin had high oxidase activity (producing hydrogen peroxide) with either L-arginine or L-lysine as a substrate and little to no oxidase activity with other L-amino acids. Hydrogen peroxide alone (without escapin or amino acids) was strongly bacteriostatic but poorly bactericidal, similar in this respect to L-arginine but different from L-lysine in the presence of escapin. Together these results suggest that there are multiple mechanisms to escapin's antimicrobial effects, with bacteriostasis resulting largely or entirely from the effects of hydrogen peroxide produced by escapin's LAAO activity, but bactericidal effects resulting from lysine-dependent mechanisms not directly involving hydrogen peroxide." (Yang et al. 2005:3609)
Learn more about this functional adaptation.
- Yang, H.; Johnson, P. M.; Ko, K. C.; Kamio, M.; Germann, M. W.; Derby, C. D.; Tai, P. C. 2005. Cloning, characterization and expression of escapin, a broadly antimicrobial FAD-containing l-amino acid oxidase from ink of the sea hare Aplysia californica. Journal of Experimental Biology. 208(18): 3609-3622.
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Molecular Biology and Genetics
Molecular Biology
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Barcode data: Aplysia californica
There are 2 barcode sequences available from BOLD and GenBank. Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species. See the BOLD taxonomy browser for more complete information about this specimen and other sequences.
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Download FASTA File
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Statistics of barcoding coverage: Aplysia californica
Public Records: 2
Species: 2
Species With Barcodes: 1
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Conservation
Conservation Status
Conservation Status
US Federal List: no special status
CITES: no special status
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Relevance to Humans and Ecosystems
Benefits
Economic Importance for Humans: Positive
Aplysia californica are used extensively in studies of behavior, reproduction, and development in such fields as chemistry, biology, and psychology.
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Wikipedia
California sea hare
The California sea hare also known as the California sea slug, scientific name Aplysia californica, is a species of sea slug, specifically a sea hare, a marine opisthobranch gastropod mollusk in the sea hare family, Aplysiidae. [1]
Contents |
Distribution
This species lives in the sea off California and northern Mexico but can be also found off the beaches of Florida.
Description
The California sea hare can be very large - the maximum recorded length is seventy-five cm (thirty inches) when crawling and thus fully extended, although most adult specimens are half this size or smaller.
A closely related species, Aplysia vaccaria, the black sea hare, can grow to be larger still.
Genomics
Sequencing of the whole genome has been approved as a priority by National Human Genome Research Institute on March 2005.[2][3] The draft genome is available on the UCSC Genome browser[4]
Life cycle
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Like all sea hares, the California sea hare is hermaphroditic, acting as male and female simultaneously during mating. The eggs are yellow, but after 8 to 9 days change into a brown color before hatching into larvae. When this annual animal is laying eggs, it has reached the end of its life. Its lifetime depends somewhat on the temperature of the water: 14-25 degrees Celsius is best, but a cooler temperature delays spawning and extends its life somewhat.
When it is considerably disturbed, as shown in the photograph at the top right, the sea hare is capable of releasing reddish-purple ink (much like an octopus does) from a gland in its mantle cavity.
Feeding habits
Like all Aplysia species, the California sea hare is herbivorous. Its diet consists primarily of red algae, which gives the animal its typically reddish or pinkish coloration.
Laboratory use
Aplysia californica has become a valuable laboratory animal, used in studies of the neurobiology of learning and memory, and is especially associated with the work of Nobel Laureate Eric Kandel.
Its ubiquity in synaptic plasticity studies can be attributed to its simple nervous system, consisting of just a few thousand large, easily-identified neurons. Despite its seemingly simple nervous system, however, Aplysia californica is capable of a variety of non-associative and associative learning tasks, including sensitization, habituation, and classical and operant conditioning. Study typically involves a reduced preparation of the gill and siphon withdrawal reflex.
References
- ^ a b Rosenberg, G.; Bouchet, P. (2011). Aplysia californica J. G. Cooper, 1863. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=240765 on 2012-03-31
- ^ Approved Sequencing Targets. Last updated 14 September 2009. Accessed 24 November 2009
- ^ National Human Genome Research Institute (1 March 2005) "NHGRI Targets 12 More Organisms for Genome Sequencing". NIH new Releases, Last Updated: 12 June 2009.
- ^ [1]
- Beeman R.D. (1963) Notes on the California species of Aplysia (Gastropoda: Opisthobranchia). The Veliger 5(4): 145-147.
- Bebbington A. (1977) Aplysiid species from Eastern Australia with notes on the Pacific Ocean Aplysiomorpha (Gastropoda, Opisthobranchia). Transactions of the Zoological Society of London 34: 87-147
- urgeon, D.; Quinn, J.F.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.; Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. (1998). Common and scientific names of aquatic invertebrates from the United States and Canada: mollusks. 2nd ed. American Fisheries Society Special Publication, 26. American Fisheries Society: Bethesda, MD (USA). ISBN 1-888569-01-8. IX, 526 + cd-rom pp.
- NIH/University of Miami National Resource for Aplysia Facility
Further reading
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- Scott F Cummins, Dirk Erpenbeck, Zhihua Zou, Charles Claudianos, Leonid L Moroz, Gregg T Nagle & Bernard M Degnan. 2009. Candidate chemoreceptor subfamilies differentially expressed in the chemosensory organs of the mollusc Aplysia. BMC Biology 2009, 7:28. doi:10.1186/1741-7007-7-28.
Moroz L. L., Ju J., Russo J. J., Puthanveetti S., Kohn A., Medina M., Walsh P. J., Birren B., Lander E. S. & Kandel E. R. (2004) "Sequencing the Aplysia Genome: a model for single cell, real-time and comparative genomics". National Human Genome Research Institute. online at http://www.genome.gov/Pages/Research/Sequencing/SeqProposals/AplysiaSeq.pdf Accessed 20 November 2009- Proekt A., Wong J., Zhurov Y., Kozlova N., Weiss K. R. & Brezina V. (7 November 2008) "Predicting Adaptive Behavior in the Environment from Central Nervous System Dynamics". PLoS ONE 3(11): e3678. doi:10.1371/journal.pone.0003678.
- Wayne N. L. & Block G. D. (1992). "Effect of Photoperiod and Temperature on Egg-Laying Behavior in a Marine Mollusk, Aplysia californica". The Biological bulletin, Marine Biological Laboratory, 182: 8-14.
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