Category Archives: Phylum Mollusca

Rostanga pulchra :The Race Rocks Taxonomy

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It is almost always found in association with the red encrusting sponge Ophlitaspongia

Physical Description:
The red sea slug is oval and commonly recognized by its bright color either red, orangish, or scarlet. But it is not uncommon to find some lighter colored species. It matches the texture and color of the sponge that it feeds on. Its body usually measures from 10 to 30 millimeters long. The back of some of the specimens can be covered with sprinkling black specks that stand out more in lighter colors. Their dorsum is covered with caryophilletic tubercules, which gives it a velvety texture. Their unique feature is their rhinophores (organs of the smell) that have vertical perfoliations.
Global Distribution: The red sea slug is dispersed all throughout the Pacific coast of North America from Alaska south to Argentina and Chile. Concentrated especially in Vancouver Island (British Columbia) and Puertecitos (Baja California)
Habitat: They are usually found on the colored red siliceous sponges they feed on, that are encrusted under rocky edges.

Feeding:
Rostanga pulchra feeds on red sponges. Ophlitaspongia pennata, Esperiopsis originalis, Plocamia karykina, and also on Acarnus erithacus and Isociona lithophoenix. It can locate the food from distance by scent. It first removes the top part of the sponge to leave a shallow groove.

Predators:
The predaceous cephalaspidean Navanax intermis can be reppelled by the Rostanga by non-acid secretions.

Reproduction:
The red sea slug is oviparous. The color of the eggs is similar to the color of the slug as well as the one of the sponge. It breads year round. The cylindrical eggs strands (2,000 to 13,000 egg capsules) are laid in a spiral pattern on the sponge they feed upon. The egg development is influenced by temperature: the warmer the shorter the development is. The eggs then develop into a larvae called veliger and drifts as plankton in the sea. The larvae will then settle and metamorphose in a suitable environment.
One interesting Fact: Like all nutribranchs, the Rostanga pulchra is hermaphrodite, which means that it has both female and male sex organs, thus their chances of meeting a potential mating partner increase. But self fertilization remains very rare.

References:
<oceanlink.island.net/oinfo/nudibranch/nudibranch.html>
<http://www.seaslugforum.net/display.cfm?id=9337>
<slugsite.us/bow/nudwk379.htm >
<www.calacademy.org/research/ izg/SFBay2K/Rostanga%20pulchra.htm>
<people.wwc.edu/…/Mollusca/GastropodaOpisthobranchia/Nudibranchia/Doridacea/Rostanga_pulchra.htm>
<www.racerocks.com/racerock/ eco/taxalab/2005/rostangap/rostangap.htm>
<www.metridium.com/monterey/nudibranchs/rostanga

<em><strong>Other<a href=”https://www.racerocks.ca/category/species/class-mollusca/”> Members of thePhylum Mollusca</a> at Race Rocks.</strong></em>

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<td><a href=”https://www.racerocks.ca/race-rocks-animals-plants/taxonomy-image-gallery/”><img class=” wp-image-17530 alignleft” src=”https://www.racerocks.ca/wp-content/uploads/2014/11/taxonomyicon-300×91.jpg” alt=”taxonomyicon” width=”201″ height=”68″></a><a href=”https://www.racerocks.ca/race-rocks-animals-plants/taxonomy-image-gallery/”><strong>Return to the Race Rocks Taxonomy

and Image File</strong></a></td>

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<td><a href=”http://pearsoncollege.ca/” target=”_blank”><img class=”alignleft wp-image-5251″ src=”https://www.racerocks.ca/wp-content/uploads/2013/05/pearsonlogo2_f2.jpg” alt=”pearsonlogo2_f2″ width=”121″ height=”73″></a><strong>The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of <a href=”http://pearsoncollege.ca/” target=”_blank”>Lester Pearson College UWC</a>. </strong><strong>It now also has contributions added by Faculty, Staff, Volunteers and<a href=”https://www.racerocks.ca/category/ecoguardians-log/visitor-observations/”> Observers </a>on the<a href=”https://www.racerocks.ca/video-cameras/” target=”_blank”> remote control</a> <a href=”https://www.racerocks.ca/video-cameras/”>webcams. </a></strong>

<strong><a href=”https://www.racerocks.ca/video-cameras/”>This file was originally started by

Rachel de Silva PC yr32

, Dec. 2005.</a></strong></td>

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Mytilus trossulus: The bay mussel

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musselpool4

These Mytilus trossulus were present in Tidepool 4 at Race Rocks in May, 2004.

 

Physical Description: Mytilus trossulus has a shiny blue-black to black or brownish thin, long shell. Its exterior is smooth with fine lines. The interior of the shell is dull blue with a darker edge. They can be up to 6 to 10 cm long, and 3 to 5 cm high.
Geographical Range: Arctic to Alaska and south to Central California. (approximate)
Habitat: Mussels attach themselves to rocks pilings & other objects in the mid-intertidal zone of shorelines where water is relatively calm. The elevation at which they can be found is limited by the sea stars in the lower intertidal zone and the risk of desiccation in the upper intertidal zone.
Feeding: Mussels are filter-feeders. They filter many litres of water by moving a set of cilia (long hair-like filaments) over their gills to produce a current-like movement and another set of cilia move the trapped food particles (plankton) into food grooves.


Reproduction: Many intertidal organisms’ reproductive cycles are adapted to the tide cycles. For Mytilus trossulus, for example, the gonads mature during the spring tides and they spawn after neap tides. The normal cycle of an invertebrate intertidal organism follows the basic pattern of fertilization and larvae. Fertilization can occur within the adult or in the water itself. A larva then develops in the female parent or in the water and it usually doesn’t look very much like the mature adult. The larvae float in the water for a few minutes up to a few months, depending on the species and reproductive cycle. They feed and grow until the end of their planktonic life, when they settle.
Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Bivalvia
Subclass Heterodonta
Order Mytiloida
Family Mytilidae
Genus Mytilus
Species trossulus
Common Name: Bay Mussel
Behaviours: Often found in large aggregations.
Adaptations to environment: To resist to mechanical stress from the wave movement, mussels have developed a strong but not permanent attachment to the rocky substrate: their byssal threads. They anchor the mussel to the rock, but can be broken and remade so it can have limited, slow movement. Mytilus trossulus also naturally has a high tolerance to waves. Most intertidal mollusks have hard shells with simple structures that aren’t likely to break under the pressure from the waves. Mussels such as Mytilus edulis, a closely related species close their valves tightly at low-tide to avoid water loss at low tide. Like all intertidal creatures, mussels must expose their fleshy parts to feed, which also exposes them to the threat of desiccation (drying out) and predators. Almost all diurnal rocky intertidal animals feed only when the tide is high and the water is covering them.

In the early 2000’s the Pearson College students in the Environmental System classes would do a lab on mussel mariculture

References: ( referenced 2005)
Shells and Shellfish of the Pacific Northwest, A Field Guide. Rick. M. Harbo, 1997

Biological Bulletin, Vol. 193, No. 2, Oct., 1997 http://www.jstor.org/stable/1542764
Balanced Environmental – Bay Mussel – Mytilus trossulus http://www.balanced.ca/hd/mussel.html

http://www.wallawalla.edu/academics/departments/biology/rosario/inverts/Mollusca/Bivalvia/Mytiloida/Mytilidae/Mytilus_trossulus.html

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.

Sara Correia, PC year 31

Amber O’Reilly, NWT PC 37

 


Ceratostoma foliata: Leafy hornmouth–The Race Rocks Taxonomy

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A leafy hornmouth exposed at low tide

We see these often in the summer in the lower intertidal zone. Their yellow egg cases also show up on the underside of rocks. They have a sharp penetrating tongue with which they can penetrate the shells of other molluscs

 

Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Gastropoda
Subclass Prosobranchia
Order Neogastropoda
Suborder Rachiglossa
Family Muricidae
Genus Ceratostoma
Species foliata
Common Name: Leafy Hornmouth

Garry Fletcher

Flabellina verrucosa The Race Rocks Taxonomy

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Flabellina verrucosa grazing on the hydroid Garveia. Photo by Ryan Murphy

In this image is Flabellina verrucosa the “Three-lined” aeolid which is seasonally abundant from Baja to Alaska (Behrens, 1991). Aeolids are opisthobranch gastropods known as sea slugs because they have lost their shells. This photo shows the nudibranch’s “oral tentacles” (bottom), ridged sensory antennae called “rhinophores”, “cerata” which contain stolen stinging cells for defense, and a “propodial tentacle”. This aeolid is common year-round at the Race Rocks Ecological Reserve where it is often observed feeding on hydroids such as Tubularia. To the left of it is thesmall Granulina m.
Macro images by Ryan Murphy

Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Gastropoda
Order Nudibranchia
Family Flabellinidae
Genus Flabellina
Species verrucosa
Common Name:nudibranch
Other molluscs 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.

Garry Fletcher

Dendronotus subramosus : Race Rocks Taxonomy

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An 8mm long nudibranch

Thanks to Karin Fletcher on iNaturalist for identifying this for us.  She indicated that D. subramosus lack lateral papillae on their rhinophore sheaths and can have brown lines along from their rhinophores along their dorsolateral processes

https://www.inaturalist.org/observations/68751217

Domain Eukarya
Kingdom Animalia
Phylum
Order 		 Mollusca
Nudibranchia
Class Gastropoda
Clade Dendronotida?
Suborder Dendronotacea?
Family Dendronotidae?
Genus Dendronotus
Species subramosus
Common Name:Stubby-fronted Dendronotus
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 2004-  (PC) Garry Fletcher

Mopalia mucosa: Mossy chiton

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chitonmossy-1

Mopalia mucosa Mossy Chiton

Size: Can range between 5 cm to 9 cm in width.

Description: Oval shaped and low and dome shaped shell. It is covered by small interlacing plates which are covered by stiff mossy dark brown hairs. The inside of the shells are of a turquoise colour. Chitons have a broad flat foot” which it uses to move and to stick to its rocky homes.

Habitat: They are usually found on rocks and in tidepools located in the middle to low intertidal zones where they are protected from heavy wave action. They can be found from the Queen Charlotte Islands in British Columbia down to California.


Diet: Red or Green algae

Activity: They can usually be found clinging to rocks. If they are somehow displaced from these, they roll into balls in order to protect their soft insides. Their foot can secrete small amounts of mucous which, along with muscular contractions, allows it to move. However, it prefers to move as little as possible and will only do so at night and when it is covered by water.

Predators: Mostly glaucous-winged gulls and black oystercatchers

Websites Consulted:
http://www.manandmollusc.net/advanced_introduction/moll101polyplacophora.html [Sep 22, 05]
http://faculty.northseattle.edu/ecauldwell/bio125/intertidal_lecture4.htm [Sep 22, 05]

http://66.102.7.104/search?q=cache:SUFBplz0MToJ:www.dohenystatebeach.org/pdffiles/tdplpack.pdf
+Mossy+Chiton+predators&hl=en [AccessedSep 22, 05]Other Members of the Class Aves 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 by Raisa Mirza, 2004

 

 

Katharina tunicata: The leather Chiton

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Katharina

Katharina tunicata the leather chiton

The black oystercatcher is the main predator of the leather chitons. at Race Rocks. We find chitons occuring abundantly in the lower intertidal zone . In the picture above they are located above a small cave in the intertidal zone on the West shore of Great Race. In order to withstand the heavy impact of waves and swell, they are able to clamp onto the rock tightly.    

Description:

Chitons are marine molluscs with oval shapes and shells divided into eight dorsal plates. The chiton Katharina lives in the medium intertidal region at Race Rocks. It is very abundant on the north and west shores of Great Race Rock.

Color:

Body to 12 cm long, elongate-oval ; all chevron-shaped shells are deeply embedded in girdle, exposed only in mid-dorsal area. The interior of valves is whiteas visible above. The girdle is thick and shiny, like black leather.

Life history:

Katharina feed on brown and red algae and on benthic diatoms which it rasps from the rocks. Young animals isolated in pools grow to a length of 15 mm in 1 year and 55 mm in 3 years. They reach sexual maturity at a weight of 4 gms (33-36mm). Spawning takes place from March to July depending on latitude, with the later spawning occuring in colder regions. The eggs are green and the life span seems to be about 3 years.

Classification:
Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Polyplacophora
Genus Katharina
Species tunicata
Common name: Leather Chiton
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.  Original by Hameeduddin Mehri (PC yr 29)

 

 

Chlamys hastata: Swimming scallop

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ah052010scallop

This image of the scallop with very bright eyes was taken by Adam Harding on a dive in June 2010

The swimming scallop is closely related to clams, oysters and cockles. Unlike some of its relatives, the swimming scallop is not sessile. The ribs of the swimming scallop are rendered rasplike by the presence of curved spines. The shell can grow up to 5 – 6 cm in height. They have beautiful, green iridescent and almost luminous eyes called ocelli that are found around the edge of the mantle in both valves. The ocelli are sensitive to light intensity and are rather complicated but do not form images. They also have sensitive tentacles that project out of the edge of the mantle.

They are usually found in subtidal areas and sometimes in shallow water. They live at depths ranging from 2 – 150 m.

Swimming scallops normally lie with their right valves against the substratum, and they may be attached periodically when they are younger by means of a byssus, a fine elastic fibre as in that secreted by mussels. Scallops are free spawning organisms. Reproduction is done through the release of sperm by males and eggs by females into the water.

Swimming scallops are filter feeders. They feed with the shell agape as it the picture above.They process water, using their ctenidia (or gills) to collect microscopic food and Oxygen from the water.

Sometimes spontaneously, and just about always when menaced by a predator, such as certain sea stars (Pisaster and Pycnopodia). They swim by a sort of jet propulsion, clapping the valves together and forcing water out through openings on both sides of the hinge. This shows in the video when the Pycnopodia is brought close to the scallop. The scallop senses the pycnopodia by a chemical sensor. The swimming scallop also swims away when there is a change in environmental conditions.

Swimming scallops are usually colonized by sponges, mostly on the left valve, that form thick coatings. The sponges provide camouflage for the scallop as well as defense against predators. The sponge’s porous nature hinders potential predators, such as sea stars from getting a good grip on the scallop, and they may also provide a repulsive chemical odor. This shows biological mutualism, where both organisms benefit in the symbiosis.

References:

Kozloff, E. N. Seashore Life of the Northern Pacific Coast .4th Edition (1996). University of Washington Press. 539 pages.

Kozloff, E. N. Marine Invertebrates of the Pacific Northwest. (1996). University of Washington Press. 370 pages.

Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Bivalvia
Order Ostreoida
Sub Order Pectinina
Family Pectinidae
Genus Chlamys
Species hastata
Common Name: Swimming Scallop

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.

Victoriano de Jesus PC year 28

 

Mytilus californianus: California Mussel

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musshand2

Very old and large Mytilus californianus in the intertidal zone at Race Rocks. This is one of the advantages of long term preservation of the area as an Ecological Reserve.

The pea crab (as one can see in the picture), Fabia subquadrata is found in 1 to 3% of California mussels along the central California coast and 18% of mussels along Vancouver Island. This is a parasite that lives within the shell, because they rob food from their host and sometimes damage one of the gills. Public health codes usually prohibit the marketing or serving of parasitized animals but since the pea crab is very tasty, organisms with this crab are sometimes sold. Moreover, in a small portion of the population you can find imperfect pearls. These are of no value. http://www.lanecc.edu/science/zonation/mussel.htm (accessed 31 January 2002)

Morris, R., P. Abbott and E. Haderlie. 1980. Intertidal Invertebrates of California. Stanford University Press, Stanford, California. 690 pages.
Domain Eukarya
Kingdom Animalia
Phylum Mollusca
Class Bivalvia
Subclass Pteriomorpha
Order Mytiloida
Family Mytilidae
Genus Mytilus
Species californianus

Common Name: California mussel
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.
Simon Michaud PC Yr. 28



Acmaea mitra: whitecap limpet– The Race Rocks taxonomy

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Introduction:The White Cap Limpet, very common on the British Columbia coast, is usually found on the lower zones as compared to the intertidal zones of other limpets. White cap limpets shells are white in colour amd rather thick in nature. The animal extends from 19-44cm (0.75-1.75″) in size.

The limpet, however, can only be seen as white after it is dead. When alive, it usually is covered by a pinkish coralline algae, Lithothamniom sp. which is also its main source of food. This forms an excellent comouflage. It’s predators include sea stars.

References: now defunct
http://web.mit.edu/corrina/tpool/limpets.html#whitecap
http://www.gastropods.com/shell_pages/m/Shell_Acmaea_mitra.html
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. January2002-Amardeep Kaur (PC yr. 27)