Category Archives: Phylum Arthropoda

Balanus glandula: Common acorn barnacle– The Race Rocks Taxonomy

Posted on by

Habitat and Appearance

Acorn barnacles are crustaceans but are commonly confused to be molluscs. Their closest living relatives are the lobsters, shrimps and prawns. These creatures are usually found growing on rocks on the seashore in low tides. The shell of the barnacle resists the oceans wave and controls the body temperature, so that the animal does not dry out.

Transportation

OLYMPUS DIGITAL CAMERA

These creatures feed  by using their antennae which have sticky ends. They feed on plankton which they sweep from the water using their feet. Their feet are the mechanism by which they filter food when underwater.

Reproduction

Barnacles are hermaphrodites; they have both male and female reproductive organs. Their reproductive organs at times are bigger then their body size by ten times. They cluster together in order to fertilize the females. They may also reproduce clones of themselves.

Eating Habits

Acorn barnacles filter zooplankton. They eat fine organic particles and plankton.

Longevity

3-5 years
Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Subphylum Crustacea
Class Maxillopoda
Infraclass Cirripedia
Superorder Thoracica
Order Sessilia
Family Balanidae
Genus Balanus
Species glandula
Common Name: Common acorn
 

reference:

http://www.fathom.com/fks/catalog/feature.jhtml?story_id=121900&featurePageNumber=2

Mehvish Mehrani PC  2002

Balanus nubilus:Giant barnacle–The Race Rocks Taxonomy

Posted on by

 

The video  is of a juvenile barnacle feeding. It was taken by Sylvia Roach through a microscope camera in the marine lab at Pearson College. The size of the barnacle can be estimated by the small skeleton shrimp which is active in the background. That amphipod is less than 1 cm in length.
Research on the associations of hydroids that live on them has been done at Race Rocks by Dr. Anita Brinckmann-Voss. In her publication on the new species Rhysia fletcheri she has included a photograph of hydroids on the valves of this animal.

Domain: Eukarya
Kingdom:Animalia
Phylum: Arthropoda
Class:Crustacea
Subclass: Cirripedia
Order: Thoracica
Suborder: Balanomorpha
Superfamily: Balanoidea
Family: Balanidae
Genus: Balanus
Species nubilus

Common Name: Giant Barnacle

Giant barnacles are commonly found on rocks, pier pilings, and hard-shelled animals in low tidal zones to 90 meters depth.

They are up to 110 mm in diameter and are not easily confused with any other species. A feature unique to the giant barnacle is the lack of longitudinal striation on the scuta. They also contain the largest individual muscle fibres known to science.

 There has also been an extended essay done on this association by a student from the college. They are often encrusted with the holdfasts of kelp. Occasionally a storm tearing at the kelp will uproot a mass of barnacles and they may end up on a beach in the masses of tangled kelp. One of the reasons we have a ban on anchoring in the reserve is that these barnacles are easily broken away from their locations on rock outcrops by a dragging anchor.

Barnacles are not usually parasites, but the weight of this one could eventually impact negatively on the mussel.

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- Aven Crawshay (PC)

Pollicipes polymerus: Goose-neck Barnacle- The Race Rocks taxonomy

Posted on by


This low tide view on the south- west corner of Great Race shows the close competition between the California mussels and the goosenecks.
LOCATION:
The gooseneck barnacle, is found in abundance in the intertidal at Race Rocks. Globally. it is found from the southern region of Alaska to Baja, California. It is attached to rocks at the high intertidal zone and all organisms in a particular area will be oriented towards the same direction. It normally occurs on wave-beaten rocks. These barnacles have undergone extensive harvesting on the shorelines of the North Pacific, in particular around urban areas. Typically our record of conservation has been poor and continued harvesting results in very little stock recruitment and consequently a diminishing stock of this species. People of Western European origin frequently have a desire to eat this species, as it tastes very much like crab.

These clumps of gooseneck barnacles line the surge channel, if you see the video on the surge channel page , you can understand how they are exposed to a food source of plankton by the surge action even when they are above the tidal level. 

 

DESCRIPTION:

It has a fleshy stalk which attaches it to rocks or floating objects. The long neck is about up to 10cm. compared to the shell which is 5 cm. long. It has a leathery appearance with small bumps. The body consists of the peduncle and capitulum. The peduncle is the attachment organ but also contains ovaries and some muscles. It is covered with tiny ossicles on short fleshy stalk. the capitulum consists of most of the animal, including all appendages except the first antennae, The capitulum is ventral.

Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class Cirripedia
Order Thoracica
Family Scalpellidae
Genus Pollicipes
Species polymerus
Common Name:Gooseneck Barnacle
–
REPRODUCTION AND FEEDING:

The organism is a hermaphrodite but they rarely undergo self fertilizaton. Cross fertilization is more common. Fertiliztion is external and it occurs in the mantle cavity. Gooseneck barnacles are filter feeders. They feed on smaller crustaceans and plankton. They do this by projecting their feathery feet called cirri to trap organisms. The cirri also act as lungs for gaseous exchange. Their main predators are the glaucous winged gull and the sea stars.

HISTORY:

Their name, gooseneck barnacle arose from the middle ages where they were thought to be developing geese which dropped off to become adult geese. As such geese were considered as fish and could be eaten on days meat was considered a taboo. Check out the patterns on the neck of the Brant Goose.

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 2002- Garry Fletcher

Scyra acutifrons: Sharp-nosed crab– The Race Rocks Taxonomy

Posted on by
 

This individual is well camouflaged and you can see the other associated organisms around it. The red circle is a serpulid worm

Geographic range is Alaska to Mexico

Size: up to 45mm (1.7 inches)

Domain Eukarya
Kingdom Animalia
Phylum Arthopoda
Subphylum Crustacea
Class Malacostrata
Superorder Eucarida
Order Decapoda
Family Epialtidae
Genus Scyra
Species acutifrons
Common Name:Sharp-nosed crab 

This is a reasonably common crab especially around the dock and higher subtidal areas. The adult males have large claws that they seem to keep folded in. The nose is flat and pointed. The crab shells are often covered with barnacles and other growth as can be seen in this picture. This species puts relatively little effort into decorating, occasionaly placing a small pieces of material on its rostrum but generally appearing to just let organisms colonize its roughened carapace. It feeds primarily on detritus and sessile invertebrates, and sometimes it associates with sea anemones. Females with eggs have been found all months but April to May and September to October. Number of eggs carried ranges fom 2,700 to 16,300.

References:

http://www3.bc.sympatico.ca/kerryw/creature/sharp.htm

Jensen G.C. 1995. Pacific Coast Crabs and Shrimps. Sea Challengers, Monterey, CA. p. 21.

Kozloff, E.N. 1983. Seashore Life of the Northern Pacific Coast. University of Washington Press. Washington. 370 pages.

Morris, R., P. Abbott, and E. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, California. 690 pages.

 

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.

Sumak Serrano (PC year 28)

Pandalus danae: Coonstripe shrimp –The Race Rocks Taxonomy

Posted on by

Ryan Murphy took the pictures on this page and followed up in getting the identifications sorted out between this shrimp and Pandalus stenoplepsis and verification from Greg Jensen of the University of Washigton.

GENERAL DESCRIPTION

The coonstripe shrimp has large eyes, a thick shell and a surface finely pitted. The color of the shrimp is transparent, milky, and has irregular stripes and spots of chocolate brown all over the body, including its antennae. The antennae are long and heavily banded. Total length of the male shrimps can become about 123mm and the females about 140mm.

HABITAT

As one of the common names suggests, the dock shrimp is often living on or by wooden wharves, in shallow water bays and inlets. The coonstripe shrimp ranges from Alaska to central California.

FEEDING

The diet of the shrimp consists mainly of amphipods, mysids and polychaete worms.

PREDATORS

Lingcods are the main predators, except for humans who exploit the shrimp in the prawn industry.

REPRODUCTION

The shrimp lives about three years. Each of the shrimps starts the life cycle as male and the first fall, breeds come. By the time the shrimp has reached its second spring, the shrimp becomes a female and breeds come fall. After that happens as a female the shrimp holds the fertilized eggs until the hatching come spring.

REFERENCES

Links:
http://www-heb.pac.dfo-mpo.gc.ca/english/programs/fhiip/species/coonstrp.htm

References:
A Bibliography of Shrimps of the Family Pandalidae by J.C. Scrivener
Shrimps of the Pacific Coast of Canada by T.H. Butler
Pacific Coast Crabs and Shrimps by Gregory C. Jensen

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.

This file was originally written by Anna Ihle Thingnaes,  Pearson College student year 28 in January 2002

 

Phyllolithodes papillosus: Heart Crab –The Race Rocks Taxonomy

Posted on by
The Heart Crab – Phyllolithodes papillosusGeneral Description:

This very distinct crab is most commonly identified by the heart shaped markings on its back, hence his common name, the Heart Crab. This triangular carapace measures from 50X60mm (female) to 90X90mm (male), and is coloured a muddy greenish brown with dark red ridges. The claws, legs and carapace are covered in prickly spines, which helps to camouflage and as a defense mechanism. The Heart Crab has three pairs of walking legs coloured dark brown and a pair of chelipeds that are dark brown with turquoise bumps. Another distinction that is evident on the Heart Crab is the two blunt horns above his eyes and a large spine between them.
Domain Eukarya
Kingdom Animal
Phylum Arthropoda
Class Malacostraca
Order Decapoda
Family Lithodidae
Genus Phyllolithodes
Species papillosus
Common Name: Heart Crab
Habitat and Range:

The Heart Crab is rarely sighted in the open nor do they inhabit the intertidal zone, instead they prefer to live subtidally in a rocky habitat, hiding in crevices with moderate exposure and strong currents. They range along the Pacific coast of North America from Alaska to California inhabiting areas as deep as 183m.

Predators and Prey:

The main predator of the Heart Crab is the octopus, and the main prey of heart crabs are sponges and sea urchins, however they are observed eating other things in captivity.

Reproduction:

All mature female Heart Crabs undergo an obligate molt occuring in the spring, from March through May. At this time of molting female are held by the chelipeds of a male. After the molting is finished and the female’s exoskeleton has hardened, the couple copulate. During this a ribbon containing spermatophores is attached around the female. The fertilization occurs within hours, after this the male separates from the female. The female then incubates her eggs for almost twelve months. Eggs are layed in the late summer, August through September. Newly laid eggs are bright yellow, orange or dark red coloured which eventually dull to a muddy brown prior to hatching.

Biotic Association:

An interesting behavior observed of the Heart Crab is the form of symbiosis,commensalism, the association between two organisms when one organism benefits and the other is neither harmed nor benefited. After molting, the Heart Crab takes shelter under the tentacle canopy of the snakelock anemone, as he is not harmed by this and the crab is protected,
References:Accessed Jan.25, 2001

http://oceanlink.island.net/oinfo/biodiversity/heartcrab.html

http://www3.bc.sypatico.ca/kerryw/creature/heart.htm

http://www.afsc.noaa.gov/kodiak/photo/triangle.htm

 

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.

Cait Caines–year 28(PC)

Euphausia Pacifica: Krill–The Race Rocks Taxonomy

Posted on by

A swarm of krill in a kelp bed. November 2006 PC Divers

Euphausia pacifica is, with Thysanoessa spinifera, the most common krill off the West coast of Vancouver Island.General description Krill are shrimp-like in appearance (Body plan of krill).The abdomen is large, and well-developed. Antennules are long, biramous and may be modified in males. Antennae are equipped with large scales. The mandibles usually have a palp and the two pairs of maxillae are small and flattened. All the thoracic legs are similar, and carry a gill formed from a typically branched epipodite and natatory setea. The last one or two pairs of legs however are often reduced or vestigial The first two pairs of pleopodes are modified as copulatory parts in males. along the British Columbia coast range up to 25 mm (1″) in length, but average 16 mm (5/8″) in length.

Habitat Krill undergo a daily or ‘diurnal’ migration, where they spend the daylight hours in the twilight depths of the ocean (~100 m or 300 feet), out of sight of their predators. As the daylight decreases, the krill rise to the surface to feed in the dark on phytoplankton. In the morning, as the sky gets brighter, the krill will return to the twilight zone. A clear day may push the krill as deep as 150 m (450 feet); on a cloudy day, the krill may be at depths of only 60 m (180 feet). Krill are not distributed evenly within a body of water; they form characteristic ‘clouds’ or patches of high biomass in some areas, whereas other areas may be devoid of krill. Euphausia pacifica is found by the Pacific ocean’s coast from the south of USA to Japan (Distribution of Euphausia pacifica).

Feeding Most krill are herbivorous, but some are omnivorous feeders. Adults migrate diurnally to the surface at night, to feed on the phytoplankton. They are exclusively filter-feeeders: water enters in a “filter” as the animal swims, and food is shoved forward to the mouth.

Reproduction Males produce spermatophores in the dilated terminal part of the sperms ducts, and transfer them to the female with the aid of the first abdominal appendages. The female stores the male’s sperm and releases it to fertilize her eggs, which appear as small bubbles in her feeding basket. Females can produce many sets of eggs (totaling more than 20 000) during the summer spawning season. Krill larvae emerge from their shells at depths of several hundred meters, where, safe from predators, they subsist on yolky materials. Eggs hatch as non-feeding nauplii and pass through protozoea, zoea, and postlarval cyrtopia stages.

Predators Their predators are mainly finfish and baleen whales (picture of krill: stomach content of Bryde whale). Krill are a large dietary proportion of many local finfish (hake, herring, rockfish, salmon) and if krill stocks should fall, finfish could be affected. Humans are also a predator. A emerging commercial krill fishery exists on the B.C. coast with a current annual limit of 500 tonnes. Krill in B.C. are harvested mainly as a feed supplement for both fish farms (gives salmon their ‘pink’ colour) and aquariums. In other areas of the world (e.g., Japan) they are also used for human consumption in limited quantities. Fresh, uncooked euphausiids have almost no taste. Frozen or dried krill develop a strong, rather discouraging flavor. They constitute the ocean’s richest source of protein and are rich in vitamins (especially vitamin A)

Biotic association Some organisms are associated with the Euphausia pacifica but it seems that few are identified. Some of the identified ones are cilliates attached to eggs of the krill, and the parasite Thalassomyces fagei that belongs to the family Ellobiopsidae (Protista (Incertae sedis))  and infests the euphausiids. The Ellopbiopsidae have been classified at various times as protistans, colorless algae, fungi, or protozoans. They are multinucleate protistans with reproductive structures outside the host (here Euphausia pacifica) and absorptive portions inside.  The organ of fixation has fine protoplasmic filaments, which are believed to absorb nutrients from the host. The parasite usually affects the maturation, molting, and growth of the Euphausia pacifica.

Traditionally, krill and other plankton have been captured with net tows. Now the use of bioacoustics allows for the detection of plankton at a much greater rate than net sampling, but does not provide any information about what species and what age classes are being sampled.
Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Subphylum Crustacea
Class Malacostraca
Subclass Eucarida
Order Euphausiacea
Family Euphausidae
Genus Euphausia
Species pacifica
Common Name: Krill

References
Kozloff, E. N. 1996. Marine Invertebrates of the Pacific Northwest. University of Washington Press, Washington, United States of America.Meglitsch, P. A. 1972. Invertebrate Zoology. 2nd edition. Oxford University Press, United States of America.Gomez Gutierrez, J. 2001.Non- identified parasite associated to Euphausia pacifica: Part I and Part
I

Other Members of the Phylum Mollusca 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. The original text for this file was written by Marie-Noelle Belanger-Levesque (Quec, Canada) PC Year 28

 

Orange hermit crab

Posted on by

In this video, the orange hermit crab inhabits the shell of an Oregon triton


The Elassochirus gilli (Benedict 1892), commonly known as the Orange Hermit Crab, is commonly found in the waters around Race Rocks. Hermit crabs are abundant around the world. They have soft rear ends that need the protection of the hard snail shell for survival. Hermit crabs carry their shell homes on their backs and tuck themselves away inside for protection using their strong stomach muscles. Sometimes, hermit crabs experience housing problems. As the crab outgrows one shell, it must find another often running into serious competitions for available homes in the right size range. Once it has found a suitable home it will not look again for some time. In any case, hermit crabs will fight for exclusive rights to empty shells. However, they will never displace a live snail from its home.In the video above, the crab inhabits the shell ot the Oregon triton snail, Fusitriton oregonensis .They have two sets of legs that they extend outside their shell for walking and two pairs of legs tucked away inside that they use to move their body around inside their shell.
The right cheliped surface of the Elassochirus gilli is smooth (without small spines) with its shield equal in length and width. The eyestalk of the crab is stout and its cornea is not inflated. The left hand is oval with a wide fixed finger. However, its greatly expanded and flattened right claw is a distinguishing feature. The walking legs of the crab are compressed and yet another distinguishing feature of the species is its bright blue upper leg. The Elassochirus gilli is usually rather uniformly orange to red.

The size of the male crab, is on average, about 20.4m in length. In this secies, the males are without paired pleopods and the females are without paired gonoppores.

The Elassochirus gilli prefers bedrock in areas of fast moving current. As such, its primary habitat is in rocky areas.
Domain Eukarya
Kingdom Animalia
Phylum Arthropoda
Class Crustacea
Order Decapoda
Infraorder Anomura
Superfamily Paguroidea
Family Paguridea
Genus Elassochirus
Species gilli
COMMON NAME: Orange Hermit Crab

WEBSITES AND REFERENCES ON ELASSOCHIRUS GILLI

http://www.oceanlink.island.net/oinfo/biodiversity/hermitcrab.html

Kozloff, Eugene N. Seashore Life of the Northern Pacific Coast, University of Washington Press (1996), p.410

Hart, Josephine F. Crabs and their Relatives of British Columbia, British Columbia Provincial Museum, Victoria (1982), p.124

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. Dec 2001- N’kiru Okagbue

 

Ligia pallasii: Sea Slater –The Race Rocks Taxonomy

Posted on by

video of sampling of populations of Ligia sp

 

During the Johan Ashuvud project 2004, students explored the intertidal with Garry. They examined various organisms as well as the artificial tidepool.

In this video, we also get a chance to meet all the students taking part in the project

The central part of this video has a section on Ligia sp.

Sexual dimorphism in body proportions is marked in L.pallasii. Males, with their large, laterally expanded ephemeral plates, have a length/width ratio of about 1.6; females and immature males are narrower, with a corresponding ratio of about 2.1. Half- moulted males are occasionally found in which the rear half of the body has moulted and is abruptly significantly wider than as yet unmoulted front half, an odd sight, usually several days after the posterior moult.On the walls of cliffs and sea caves, the larger and broader males often cover and shield the females and juveniles.

L.Pallassi prefers sea cliffs. At Race Rocks, the loose upper intertidal rocks and crevasses on the Western side of the main island provide ideal habitat. There are differences in the osmoregulatory responses shown by these species associated with their behavior and ecology.The slower -moving pallasii lives permanently in cool, moist habitats characterized by fluctuating hypo-saline condition. L.Pallasii are air breathers with gill-like pleopods not equipped with tracheal trees.The respiratory pleopods must be kept moist to function properly.This is done by immersion or by dipping the tail in water in such away that the uropods serve as capillary siphons.

Ligia species are fed upon by birds, especially gulls, and by the intertidal crab. Life span of L.pallasii is 1.5 to 2 years , with breeding occurring in spring and early summer, and the average brood size is 48 plus or minus 11 young.The overall sex ratio is 1:1.

Domain Eukarya
Kingdom Animalia
Phylum or Division Arthropods
Class Crustacea (crustaceans)
Order Isopoda
Family Ligiidae
Genus Ligia
Species pallasii
COMMON NAME:sea slater

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. Dec 2005- Palwasha Hussain Khel