Category Archives: Invertebrate video

Fabia subquadrata: The Pea Crab — The Race Rocks Taxonomy

Posted on by

 

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)

The Giant Pacific Octopus

Posted on by

Giant PacificOctopus frequently appear at Race Rocks in the subtidal waters. They are also seen occasionally washed up in the intertidal zone where they contribute to the energy flow of the gulls and eagles. This individual which had died recentlyin June 2002, became the subject of a webcast and an impromptu dissection on the shore.

 

Oregonia gracilis: Decorator Crab — The Race Rocks Taxonomy

Posted on by

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)

Cyanea ferruginea: The Pacific Lion’s Mane Jellyfish The Race Rocks Taxonomy

Posted on by

Cyanea ferruginea or the sea blubber is a common jelly fish in the Strait of Juan de Fuca. It often comes into calm water or bays when it is nearing the end of it’s lifespan. This one was spotted off the college docks in Pedder Bay. Laura Verhegge manipulates it to enable us to see the internal structure of the animal.  We have just changed this name as the result of a correction on iNaturalist.  ptreviously we had had the species as C.capillata

 

Introduction: This marine animal differs from those in other invertebrate phylums due to the existence of a true mouth and digestive cavity. It contains two layers of cells, the outer covering, and the inner covering for the digestive cavity. The Mesogloea (a non-cellular layer) is found between these two cell walls. The Cyanea capillata, like most jellyfish can exist in both a polyp and medusae form.

Identification: Cyanea can vary greatly in size. The bell ranges from approximatley 2 meters in diameter, to 50 centimeters. The larger the diameter of the bell, the higher latitude it is found at. Also, the larger the Cyanea, the darker the colour. For example, large Cyanea’s are deep red and purple, while the smaller ones are a lighter, yellowish brown colour. There is eight clusters of tentacles that are found in an arrangement of rows. In one cluster, there may be approximately 150 tentacles, some with the ability to project up to 30 meters. Around the opening of the gastric cavity is found a series of short oral arms. The arms are highly folded, and are used in the digestion of prey.

Habitat: This marine animal exists on the west coast of North America, falling between the region of Alaska to Washington. Occasionally it may be found as low as Oregon, but it does not have the capacity to survive in warmer climatic conditions such as those in California. Within its salt water environment, it serves as both prey and predator, continuing the marine life cycle.

Digestion: The Cyanea is equipped with nematocysts on is tentacles to help sting, and immobilize its prey. It is these nematocysts that sting humans when the Cyanea is touched. This sting can last up to four or five hours. Cyanea is one of the most common jelly fishes on the Pacific West Coast known for stinging. The most common prey for theCyanea is zooplankton. Once the prey has been stung by the nematocysts, the oral arms relocate the prey into the gastric cavity for digestion. As this process continues with the use of cilia living, food is transferred through the radial canals. The purpose of these canals is to control the movement of nutrients obtained from the food, and oxygen within the organism. Along with being a predator Cyanea is also found to be prey for such organisms as scyphomedusae, as well as various sea birds, turtles and fishes.

Movement: Cyanea capillata swims throughout its salt water environment by using contractions amongst its circular and radial muscles. These muscles are located in the bell of the jellyfish. A more simplistic way to describe this process is the expulsion of water from the bell, creating a propelling movement forward. This is followed by the relaxation of the muscles, and its return to is resting shape of a bell. At the end of the power stoke in this swimming process, the Cyanea is said to resemble an eight pointed star.

Reproduction: This particular jelly fish uses both asexual and sexual methods of reproduction. They undertake both a polyp and medusae life cycle. The tail of the Cyanea capillata is the production site for the larvae, that later on attach and form into a polyp. These polyp will divide off into medusae. This occurrence of division is asexual.

Natural History: Cyanea capillata has a life expectancy of approximately 1 year. During its life span, it can most commonly be seen during the summer, especially near the fall.

Relation to Race Rocks: The Cyanea is often seen at Race Rocks, in the shallow waters, but not on beaches, although occasionally one gets washed up in the boat launch area. It is frequently in Race Passage and at Race Rocks.

Referennces:

1. Mills, Claudia and Wrobel, David, Pacific Coast Pelagic Invertebrates – A guide to the common gelatinous Animals , Monterrey Bay Aquarium, 1998.
2.  Kozloff, Eugene N., Sea Shore life of Puget Sound, the Strait of Georgia, and the San Juan Archipelago, University Washington Press, 1973.

Return to the Race Rocks Taxonomy Index

This file is provided as part of a collaborative effort by the students,faculty, staff and volunteers of Lester B. Pearson College December 2002 Beth SullyPC yr. 29

 

 

 

Hippasteria spinosa:The Spiny Sea star–The Race Rocks taxonomy

Posted on by

 

Spiny Stars are rarely seen by divers at Race Rocks. Ryan demonstrates one to the Colwood Elementary a school class

Description:

The Hippasteria spinosa is an uncommon, 5 armed, aboral surfaced sea star. Its most marginal plates have 2 spines and it has some conspicuous bivalved pedicellariae.

Its colour is orange to vermillion, which intensifies at the short, stalky arms (R/r=1.7 to 2.6) and becomes whiter near the mouth. Usually in the subtidal region at depths of 100 to 500 metres, it can sometimes be found on the beach. It is characterized by having all its plates covered with granules, giving it a spiny, STELLATE look.The mouth has 4 or 5 marginal spines and a slightly wider than high mouth (elipsis shape).

Habitat and region

Can be found from Kodiak Island to Southern of California and the Sea of Okhotsk and is more common around the west coast of Vancouver Island and other exposed coastal parts. It prefers muddy, shallow environments and can also be found in shell and rock.

References:
Taxonomy: Marine Invertebrates of the Pacific Northwest; Kozloff, Eugene, University of Washington Press, 1996 Edition, USA

 

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)

Sea pen: Ptilosarcus gurneyi-The Race Rocks Taxonomy

Posted on by

(Ed Note: The scientific name at the start of the video is not correct.) The sea pen, Ptilosarcus gurneyi, is a colonial cnidarian in the same class as the anemone, the anthozoa. One polyp has been modified to form the body,  while the fringes of the “feather” contain numerous small feeding polyps. Typically we find it living in a mud/sand substrate. It is rare around Race Rocks. The only population we have found is this one with a few individuals occurring at 15 metres on the North-West corner of Great Race Island. Note the small burrowing tubeworms in the mud around the organism. This specimen was videoed by Wynne Lawrence and Jean-Olivier Dalphond, both students at the Lester B. Pearson College.

General Description:

The sea pen, Ptilosarcus gurneyi, is a colonial cnidaria in the same class as the anemone, the anthozoa. One polyp has been modified to form the body while the fringes of the “feather” contain numerous small feeding polyps.

Habital:

Sea pens are marine organisms: typically they are found living in a mud/sand substrate at least 3 inches (7.6 cm) deep. It is rare around Race Rocks, with a few individuals occuring on the North-West corner of Great Race Island. Note the small burrowing tubeworms in the mud around the organism.

Feeding:

The polyps feed on detritus, zooplankton (baby artemia), and possibly (according to The Reef Aquarium Vol. Two) phytoplankton.You should offer your Sea Pen Artemia nauplii, Daphnia, pulverized flake food, and detritus stirred up from the bottom of the tank.

Predator:

Predators of the sea pen are two nudibranchs, one the very large 3 inches(7cm) nudibranch, Armina californica and the other Mediaster aequalis, Rose Star Crossaster papposus and the Leather Star Dermasterras imbriacata.

Reproduction:

We don’t know the reproduction of sea pens whether by sexual or asexual means.

References:
http://www.fishroom.com/library/seapen.html
http://www.lanecc.edu/science/zonation/seapen.htm

Kingdom: Animalia
Phylum: Cnidaria
Class: Anthozoa
Subclass: Octocorallia
Order: Pennatulacea Verrill, 1865
Suborder :Subsessiliflorae
Family :Pennatulidae Ehrenberg, 1834
Genus:Ptilosarcus
species:gurneyi
(Ptilosarcus gurneyi)
Common name: orange sea pen

Return to the Race Rocks Taxonomy and Image Gallery

Other Members of the Class Anthozoa 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. 

Original: Dec 2002, Joshua Columbus ( Burma) year PC yr 29).  

additions by G.Fletcher 2018

 

Hydrocoral at Race Rocks and Alberto Lindner

Posted on by

Alberto Lindner is studying the systematics and evolution of hydrocorals using morphological and molecular biology methods for his Ph.D. thesis. He visited Race Rocks in the summer of 2002. The occurrence of hydrocoral in the low intertidal zone is an unusual occurrence on the Pacific West Coast and Alberto is aiming to help us in the identification of the different colored clones of the animal. His supervisor and advisors are Dr. Stephen Cairns (Smithsonian) , Dr.Cliff Cunningham ( Duke University) and Dr. Dale Calder (Royal Ontario Museum) This is part of a program of training young zoologists in established and new methods of systematics Alberto comes from Brazil, having completed a Master’s degree in the University of São Paulo.

Alberto was introduced to us by Dr. Anita Brinkmann-Voss

See  Hydrocorals in The Race Rock Taxonomy

After returning to his lab and doing further analysis, Alberto reported that “It is pretty safe to say that the purple and pink color morphs of Stylaster corals (Allopora) from Race Rocks are the same species”. He has also noted the same result with deep-sea species from the Aleutians, as the orange and pink forms there do not separate the species.

Link to Alberto’s website.

Westmont Montessori Class Visits Race Rocks as part of our Schools Project

Posted on by

In June, 2002 the grade six students of Nadine Cruikshank’s class at Westmont Montessori school in Metchosin came out to Race Rocks to participate in a live webcast. Pearson College students Ben, Joe, Kiprop and former student Ryan who were staying at Race Rocks for the Johan Asuvud Race Rocks 2002 Project introduce them to the ecology and the history of Race Rocks. (17 minutes)

Eudistylia vancouveri: feather duster tubeworm –The Race Rocks Taxonomy

Posted on by

 

The Feather Duster Tube worm is often associated with floating docks on the southern part of Vancouver Island. At Race Rocks, there are no floating docks but Eudistylia inhabits the protected rock crevasses of the lower intertidal zone. It can not withstand drying out too long so being in this tidal level will provide a maximum of an hour exposure at the lowest tides. While exposed in the air, their feather like gills are retracted, and the leathery parchment -like tubes are pinched closed at the opening. Underwater, the gills when released, are often banded a deep red and purple colour.

 

Domain Eukarya
Kingdom Animalia
Phylum Annelida
Class Polychaeta
Order Canalipalpata
Suborder Sabellida
Family Sabellidae
Genus Eudistylia
Species vancouveri
Common Name: Northern Feather Duster Wor

GF photo, 2007

Other Members of the Phylum Annelida 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.

 June 2002  Garry Fletcher (PC)