Category Archives: Phylum Arthropoda

Semibalanus carriosus: Thatched barnacle–The Race Rocks Taxonomy

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Student pointing to thatched barnacles . Note goose- neck barnacles on the rock above.

Student pointing to thatched barnacles . Note goose- neck barnacles on the rock above.

Thatched barnacles are at a relatively low level in the intertidal zone as can be sen in this photo of their habitat.

 

 

 

 

Domain Eukarya
Kingdom
Phylum
Class
Order
Family

Genus Semibalanus
Species carriosus
Common Name: Thatched barnacle

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Other Members of the Phylum Arthropoda at Race Rocks.

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pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

 

Unidentified “Clear” Shrimp? The Race Rocks Taxonomy

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Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class Malacostraca
Order Decapoda
Family
Genus
Species
Common Name: Clear Shrimp
Unidentified
taxonomyiconReturn to the Race Rocks Taxonomy and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

 

Gammarus sp. : Scud–The Race Rocks taxonomy

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From Wikkipedias: Gammarus is an amphipod crustacean genus in the family Gammaridae. It contains more than 200 described species, making it one of the most speciose genera of crustaceans.[2] Different species have different optimal conditions, particularly in terms of salinity, and different tolerances; Gammarus pulex, for instance, is a purely freshwater species, while Gammarus locusta is estuarine, only living where the salinity is greater than 25‰.[3] Species of Gammarus are the typical “scuds” of North America and range widely throughout the Holarctic. A considerable number are also found southwards into the Northern Hemisphere tropics, particularly in Southeast Asia.[4]
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostraca
Order: Amphipoda
Suborder: Senticaudata
Family: Gammaridae
Genus: Gammarus Fabricius, 1775
Type species
Gammarus pulex Linnaeus, 1758 [1]
Other Members of the Phylum Arthropoda at Race Rocks.
taxonomyiconReturn to the Race Rocks Taxonomy and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

Hemigrapsus nudus-Purple Shore Crab– The Race Rocks Taxonomy

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At the mid-intertidal rocky shore level on southern Vancouver Island, you will frequently find this as the most common species of shorecrab. At Race Rocks, they particularly like the loose rock habitat of the intertidal area beside the boat ramp on the jetty. The maximum size this crab attains is that shown in the video, about a 2cm. width of carapace. Thanks to Taarini Chopra and the environmental systems class for this video done as part of a study on biotic associations of the invertebrates at Race Rocks. This species is a particularly good example because of the parasites it often carries


Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class Malacostraca
Order Decapoda
Suborder Pleocymata
Family Grapsidae
Genus Hemigrapsus
Species nudus
Common Name: Purple shore crab

Other Members of the Phylum Arthropoda at Race Rocks 
taxonomyiconReturn to the Race Rocks Taxonomy and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

March October 2003- Taarini Chopra (PC yr 27)

Cryptolithodes sitchensis: turtle crab –The Race Rocks taxonomy

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turtle crab (Cryptolithodes sitchensis). Photos b y Laura Verhegge 

 

Appearance: Cryptolithodes sitchensis range from bright red or orange to gray and even white colors. The average size of an adult turtle crab is 90mm (3.6in). A distinctive characteristic of the crab is that its legs are completely covered by its shell.

Distribution: The turtle crab can be found from Sitka, Alaska along the coast to Point Lowa, California,
Domain Eukarya
Kingdom Animalia
Phylum: Arthropoda
Subphylum Crustacea
Class Malacostraca
Order Decapoda
Suborder: Pleocyemata
Family: Lithodidae
Superfamily: Paguroidea
Genus Cryptolithodes
Species sitchensis
Common Name:Turtle Crab or Umbrella Crab

Where at Race Rocks? This species can be found at Race Rocks and on Rosedale Reef. In the summer of 1997, Donna Gibbs had noted specimens of Cryptolithodes sitchensis. in her inventory.

Habitat: This particular type of crab is usually found on bedrock from the low intertidal zone to 17m (56ft), in semi-protected area on or near the outer coast. Furthermore, the turtle crab rarely leaves its home.

Feeding: While on bedrock, the turtle crab grazes and feeds on sessile organisms, particularly algae.

Reproduction: The turtle crab reproduces sexually, using the molting cycle. There are six stages in the development of the turtle crab: Eggs, Prezoea, Zoea, Megalops, Juvenile Instar, Adult Crab.

Interesting Adaptation: Its distinctive shell allows it to camouflage itself into its surroundings. It is often mistaken for an old clam shell or patch or coralline algae.

Other Members of the Phylum Arthropoda at Race Rocks 
taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

AJ (PC year30)

Neomolgus littoralis: the red velvet mite

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The video above was taken by Peg 15 on the North Shore of Great Race Rock where the students of a biology class were doing an intertidal transect. We often find Neomolgus at this elevation, and it is one of the few invertebrates inhabiting the top range of the spray zone.

Neomolgus is a tiny mite looking like a little red dot moving across rocks or other hard surfaces. Its diameter is 3mm. Mites are like spiders and ticks in that they have four pairs of legs. At Race Rocks, it is especially common among the bare rocks out on the North West corner by peg15.

Neomolgus has a large distribution in the northern hemisphere. It moves very actively and responds very negatively to the approach of a human finger. It uses its long snout for piercing small flies and sucking their juices.

Links:http://www.beachwatchers.wsu.edu/ezidweb/neomol01.htm

Kozlof : SeashoreLife of the Northern Pacific Coast.

Lamb and Hanby, Marine Life of the Pacific Northwest, page 276

Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class arachnida
Order Acari
Trombidiformes
Family Bdellidae
Genus Neomolgus
Species littoralis
Common Name:red velvet mite

 

Other Members of the Phylum Arthropoda at Race Rocks 
taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

 March October 2003-  Rahilla (PC)

Fabia subquadrata: The Pea Crab — The Race Rocks Taxonomy

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Jeremias, Carmen and Felix remove a pea crab from the mantle of a California Mussel.
At Race Rocks there are many large mussels; (up to 30 cm) with such parasite inside.

 

Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class Crustacea
Order Decapoda
Family Pinnotheridae
Genus Fabia
Species subquadrata
Common Name:Pea crab

Brief Definition

Pea/Mussel crabs are tiny creatures that live as symbionts, on or in the bodies of other invertebrates (bivalves)

Size

As their common name implies, Pea crabs are small creatures. The female pea crabs are distinctively larger than the male crabs, reachimg a size of 22mm (0.8in). The males however reach a size of 7.3mm (0.3in).

Habitat

Pea crabs occupy 2 different niches during their lifetime. Prior to and after their mating season, the adult female lives in a host. Host species include:

California mussels ( Mytilus californianus )

horse mussels ( Modiolus modiolus ).

Mytilus edulis

As well as other species of bivalves including scallops, oysters, cockles and clams.

The juvenile crabs also occupy a host before they become mature.

Range

These crabs live in mainly the northern hemisphere waters.

Including eastern and western U.S.(Akutan Pass, in the waters of Alaska to Ensenada.), Europe, Argentina and British Columbia, Canada.

It is found in 1 to 3% of California mussels along the central California coast, and 18% of mussels along Vancouver Island, BC, Canada.

Adaptation

Mussel crabs live in specific hosts because each crab responds positively to only certain chemicals that their hosts emit. In this way, they are able to infest the hosts that have the right conditions for them to survive. While in the host, these crabs do not posses an exokeleton. This is beacause the hosts provide them with protection against predators and other harmful external factors. However, when they leave their host to mate in the planktonic environment, the adult crabs grow an exoskeleton to protect their membranous carapace. These crabs also posses 10 legs, of which 2 of them develop into large and powerful claws to help fend off predators when exposed in the plankton, and to also help in the grasping of food.

Relationship with Host

The relationship that exists between the mussel crab and the bivalve is a symbiotic one. The advantage of this relationship is that the crab is protected while it scavenges the necessary nutrients needed by it, in the host. The crab however at times robs its host of a large mount of food and it also feeds off the protective mucus layers that cover the host’s tender tissues.This results in the mussel’s gills been injured. When this occurs the relationship becomes a parasitic one as the crab benefits while the host is affected negatively. Hence they are classified as parasites.

Precautions are taken when animals such as Mya arenaria, Placopecten magellanicus, Argopecten irradians and oysters are sold as to not have a pea crab inside it.

Reproduction and Lifecycle

The pea crabs’ life cycle has two distinct stages. These two stages are so different that in fact they were classified into two different genera.

The first stage comprises of the large, adult females that have soft membranous crapaces. These adults occupy a host each and they produce larvae that mature into the second stage. In the second stage, the offspring (larvae) of the female (that she had produced inside her host) grow up into adults of both sexes.Having reached maturity, they leave their hosts and join swarms in the water to mate. At this stage the pea crabs look more ‘traditional’. They have hard shells, strong legs (for swimming) and at the front of the carapace they have thick hair. Upon completion of mating, the female returns to her host. For a period of 21-25 weeks, she goes through 5 molts before reaching maturity. The female can inhabit here for up to a year, producing larvae from eggs that where fertilised by sperm from her single mating and then the cycle begins again. The mating takes place in late May.

Note: the male after mating dies.

References

Source 1: Pacific Coast Crabs and Shrimps by Gregory.C. Jensen, Ph.D

Source 2: Port Townsend Marine Science Center. Marine & Natural History Exihibits

Source 3: http://www.ptmsc.org/html/peacrabs.html

Source 4: http://life.bio.sunysb.edu/~jmatth/Science.htm

Source 5: http://www.pac.dfo-mpo.gc.ca/sci/shelldis/pages/pcbmu_e.htm

Source 6: http://www.indian-ocean.org/bioinformatics/crabs/crabs/tex1.html

Other Members of the Phylum Arthropoda at Race Rocks 
taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

October 2003-  Michelle(PC)

Tigriopus californicus: Harpacticoid–The Race Rocks Taxonomy

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We frequently find abundant populations of Harpacticoids in the high tidepools number 10, 7 and 2 at Race Rocks

Populations can fluctuate widely through the seasons.. Since pool 7 is at the highest elevation, it may not receive new inputs of seawater unless there is a wind from the West. In the summer, with no rain, and with elevated temperatures, this shallow pool will develop salt crystals. At that time, the only population of Tigriopus californicus is in pool 2 which is deeper and shaded, and in pool 10 which is small but shaded. Later on, in October, pool 7 may have an abundant population concentrated along the vertical walls of the pool. In this photo, The photo above was taken on a compound microscope at 10 power, but it has been enlarged considerably by photomicrography

In this photo Gerald has scooped up a sample from pool 10,where they are visible to the naked eye as small moving reddish dots.

 

 

 

Research done on this organism by the student T.C. Merchant at the Hopkins Marine Station of Stanford University in 1977, refers to this unique osmoregulatory adaptation for this Euryhaline environment.

“Abstract: Tigriopus californicus exhibit a unique osmoregulatory behavior which is highly adaptive in the high splash pool habitat. They conform osmotically in intermediate salinities and regulate hypo and hyper osmotically in high and low salinities respectively. Gut fluid appears to remain isosmotic with the environment. Evidence is presented to suggest the gut may be a regulatory surface in Tigriopus. The range of osmoconformance depends on the length of acclimation to a given salinity. O2 consumption in Tigriopus is high in low salinities decreasing as salinity rises. Metabolism appears not to change significantly over the conforming range 35 to 60 0/00″

Other interesting research on this organism has been on its Phylogeny. Research done in southern latitudes on Tigriopus revealed one of the highest levels of mitochondrial DNA differentiation ever reported among conspecific populations. S.Edmands ( Molecular Ecology,Volume 10 Page 1743  – July 2001) showed that populations from Puget Sound northward had significantly reduced levels of within-population variation based on cytochrome oxidase I sequences. These patterns are hypothesized to result from the contraction and expansion of populations driven by recent ice ages.

The Pesticide Action Network North America.lists extensive results of toxicity studies with Pesticides using Tigriopus californicus.

Dr. Maarten Voordouw working with Dr.Brad Anholt of the University of Victoria has researched the evolution of Sex ratios in Tigriopus californicus. He found there to be a variation in offspring sex ratio larger than the binomial expectation, and that females produce male-biased clutches at higher temperatures. The trait is heritable and is transmitted primarily through the paternal line. http://web.uvic.ca/~banholt/anhlabsite/tigs.html

Other Members of the Phylum Arthropoda at Race Rocks.

taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.   G.Fletcher

 

Oregonia gracilis: Decorator Crab — The Race Rocks Taxonomy

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Decorator crabs are common in the intertidal and subtidal areas at Race Rocs. Their habit of attaching bits of algae, or shell on their carapace makes them well camouflaged. They are a small crab, only up to 2-3 cm width in their carapace. 

In 1889, William Bateson observed in detail the way that decorator crabs fix materials on their backs. He noted that “[t]he whole proceeding is most human and purposeful”, and that if a Stenorhynchus crab is cleaned, it will “immediately begin to clothe itself again with the same care and precision as before”.[2](Wikipedia)
Domain Eukarya
Kingdom: Animalia
Phylum: Arthropoda
Subphylum: Crustacea
Class: Malacostrata
Order: Decapoda
Family: Majidae
Genus Oregonia
Species gracilis
Common Name: Decorator Crab
 

Other Members of the Phylum Arthropoda at Race Rocks 
taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.

 name 2002 (PC)

Pagurus hirsuitiusculus: hairy hermit crab–The Race Rocks Taxonomy

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This video shows the two species, the Hairy hermit crab Pagurus hirsuitiusculus and the sponge Suberites in a commensal biotic association.

hairy-pagurus

Hairy Hermit Crab: photo by Ryan Murphy

bandedantennae

A distinguishing feature of the hairy hermit crab is te banded antennae shown in this image from the video

The specimens studied were collected at  Race Rocks in November of 2002. They were unique specimens because of their choice of home. Usually hermit crabs use the shells of snails that have died then discard them as they grow larger in place of a bigger shell. However, these Hairy Hermit Crabs had decided to become the hermit crabs of Hermit Crab Sponges.

Hermit Crab Sponges, Suberites.spp are sponges that attach themselves to a mobile animal who has a solid exoskeleton, usually a snail or crab. In the hermit crab’s case, the sponge begins to grow on their adopted home by first thinly encrusting the shells. As the sponge grows, it begins to cover the shell and can surround it completely, sometimes making locomotion difficult for the crab. Once the sponge has buried the shell inside itself, the hermit crab leaves its shell to occupy a chamber in the sponge it had hollowed out.

CLASSIFICATION:
Domain: Eukarya
Kingdom: Animalia
Phylum: Arthropoda
Class: Crustacea
Order: Decapoda
Superfamily: Paguridea
Family: Paguridea
Genus: Pagurus
Species: hirsuitiusculus
Pagurus hirsuitiusculus
Common Name: Hairy Hermit Crab

Other Members of the Phylum Arthropoda at Race Rocks.

taxonomyiconReturn to the Race Rocks Taxonomy
and Image File
pearsonlogo2_f2The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams.