A trip to the Vancouver Aquarium Marine Science Centre will expose you to an amazing variety of marine animals and will allow you to assess and appreciate the knowedge you have earned by taking BIOL 205.

A trip to nearby Stanley Park will expose you to a somewhat limited, but still interesting, array of marine invertebrates living on the Vancouver Harbour foreshore. The following animals are likely to be seen (Note: all sizes given are for adult individuals):


Brockton Point, Stanley Park

Porifera
Halichondria
panicea		 Yellow encrusting sponge. This view is of an open-coast individual, that is green due to its photosynthetic zoochlorellae symbiont. At Stanley Park, the species is more yellow in colour and not so compressed in form.

Size: clumps 2 to 3 cm in height


Cnidaria
Obelia sp. Colonial hydroid. This genus exists in small bush-like growths, approximately 2 -4 cm in height, and can be found attached to rocks, seaweeds, barnacles, or other growth.
Urticina sp. Members of this genus may be found on the lower sides of rocks in the low-intertidal zone. Specimens at Stanley Park are likely to be small ones.

Size: to 20 cm in height

Platyhelminthes
Freemania litoricola This small brownish-coloured polyclad flatworm lives on the undersides of rocks in the mid- to low-intertidal region. It apparently feeds on barnacles.

Size: to 4 cm

Nemertea
Nemerteans One or two species of ribbon-worms may be seen amongst the mussel and barnacle growth. Nemertines are carnivorous and possess a highly extensible proboscis for attacking and engulfing a variety of invertebrate prey.

Size: 30 -50 cm in length, highly variable

Annelida
Eudistylia polymorpha Tubeworm. For reason presumably of nutrient enrichment of the Harbour water, this worm is one of the commonest residents of the intertidal area at Brockton Point. It filter-feeds on organic particles using its crown of branchial tentacles.

Size: 20 cm
Artonöe sp. This and other scaleworms (polychaetes) such as Halosydna sp. and Harmothöe sp. can be found living commensally with the sea star Evasterias troschelii, or free-living, depending on the species. It probably behaves more like a parasite than a true commensal, although its main negative effects on its host are benign, involving mostly the sharing of the host's meal.

Size: 2 - 3 cm

Nephtys sp. The sand-worm can be found under rocks in burrows in the sand or amongst mussel clumps. It is carnivorous on other small invertebrates, using its large pincer-like mandibles to subdue its prey.

Size: 20 cm

Mollusca
Littorina scutulata Shown here is L. sitikana. Littorrina scutulata is usually smaller in size, more pointy-shaped, and has a reticulated (checker-board) pattern on its shell. Both species live in the splash zone at the top of the shore, where they feed on macro-algae and diatoms.

Size: 15 mm

Collisella digitalis		 Lives in the high intertidal area on rocks. The distinctive ribs on this algae-eating limpet help to identify it. Its diet is mainly diatom coatings on the rocks and algal sporelings.

Size: 25 mm
Notoacmea scutum The dinner-plate limpet feeds on algae and diatoms and is usually found in or around tidepools.

Size: 4 cm
Onchidoris bilamellata This nudibranch is found on and amongst barnacles, on which it feeds.

Size: 2 cm
Mya arenaria The American soft-shell clam has a whitish or chalky-grey coloured shell. It was introduced from the east coast of North America.

Size: 7 cm
Crassostrea gigas The Japanese oyster was introduced into the Ladysmith area of Vancouver Island in 1912. It presently represents the mainstay of the fairly lucrative B.C. oyster-culture industry.

Size: to 20 cm
Katharina tunicata The black-leather chiton feeds on diatoms and selected macro-algae from mid-tide level to subtidal regions.

Size: 10 cm
Mytilus trossulus This mussel inhabits the mid-to low-intertidal area of harbours, bays, and estuaries. It attaches to rocks with its many byssus threads.

Size: 5 cm
Nucella lamellosa with egg cases The common dog-whelk is making a comeback in the Stanley Park region after being completely decimated in the mid-1970¹s by an affliction known as imposex. All females in the population turned to dysfunctional males, a response to a certain anti-fouling paint used on boat hulls containing the metal tin (tributyltin). Nucella is a predator on mussels and barnacles, drilling into its prey with its radula.

Size: 5 cm

Arthropoda
Balanus glandula This is the largest barnacle in the intertidal area of Stanley Park, reaching up to 1.5 cm in diameter. When crowded, individuals become longer and possess weaker shells.

Size: 2 cm high
Chthamalus dalli This is a much smaller barnacle than Balanus glandula. It is brownish in colour and the four main covering plates form a distinctive cross-shape when closed. Note in the photograph the poor survival of many of the spat or juveniles.

Size: 5 mm dia
Hemigrapsus nudus This is one of two shore-crab species found in this region. It is characterized by its reddish coloration and hairless legs. Both Hemigrapsus species are omnivorous scavengers.

Size: 3 cm carapace width
Hemigrapsus oregensis Usually smaller than its congenor, H. nudus, is mottled greyish-green in colour, has hairy legs, and lives in somewhat more sedimenty conditions than does H. nudus.

Size: 25 mm carapace width
Cancer productus The red rock crab is the largest crab in the area, reaching up to 15 cm in carapace width. It feeds mainly on bivalves and snails.

Idotea wosnesenskii This distinctive olive green-coloured isopod can be found on rocks and seaweed in the Fucus zone. It is herbivorous, feeding on diatoms and small algae.

Size: 35 mm
Ligia pallasii This slate-grey semiterrestrial isopod can occasionally be seen on the seawall, above the high-tide level. It shuns immersion, but is imperfectly adapted to life on land; hence, inhabits a narrow vertical range of habitat extending only one or a few meters above the tide-mark. It is mainly herbivorous, and favours diatoms and a variety of macro-algae.

Size: 40 mm
Gnorosphaeroma oregonensis This species is mottled-grey in colour, and is much smaller and pudgier than Idotea , or Ligia . It grows to about 1 cm in length, and is found more commonly in areas of freshwater seepage. It rolls up into a ball when disturbed. It is probably mainly a scavenger, but perhaps favouring plant matter.
Pagaris hirsutiusculus this scavenging hermit crab is the commonest species of hermit crab to be found in the Stanley Park region.

Echinodermata
Strongylocentrotus droebachiensis The green sea urchin is one of several related urchin species found in B.C. waters. It eats mainly seaweeds.

Size: 8 cm test diameter

Pisaster ochraceus The common ochre star. Feeds on mussels and barnacles.

Size: 25 cm
Evastarias troschelli The mottled star is found in low intertidal regions where it feeds on a variety of shelled and other invertebrates. This individual is in the process of growing three new arms.

Size: 25 cm
Parastichopus californicus
with feces		 This brownish-coloured sea cucumber may be seen in the lower region of the intertidal area. It is a scavenger of organic matter, and eats a lot of sand and mud.

Size: to 40 cm in length
Pycnopodia heliathoides This, the world's largest-diameter seastar, is a fast-moving predator of many invertebrates, including bivalves, sea urchins, chitions, snails, hermit crabs, brachyuran crabs, worms, sea cucumbers, and other sea stars. It also scavenges on dead animals.

Size: to1 m in diameter
Equipment needed for the field trip:
  • flashlight
  • boots
  • warm clothes
  • come prepared for rain!