The intertidal rocky shore 

identifying red seaweeds of the intertidal rocky shore 

By Dr J Floor Anthoni (2007)
Red seaweeds are most suited to grow in dark places and in the deep. Yet many species survive well near the surface and in rock pools of the intertidal rocky shore. It is difficult to tell the various species apart. Many red seaweeds are intrically branched, forming beautiful patterns when spread out over a white page of paper.
  • red seaweeds: Red seaweeds are finely structured, weak and suitable for deeper waters.
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red seaweeds
Red seaweeds have a red pigment that absorbs blue light, which penetrates deepest in the sea. As a result, red seaweeds can be found deeper than brown and green seaweeds. But even in the sunlit shallows of the rocky shore, one can find a number of species. The red seaweeds comprise the largest number of seaweeds in New Zealand.
0703060: blood crust (Ralfsia verrucosa) forms a brown to deep red wrinkled crust, surviving extreme desiccation. the barnacle is the sheet barnacle or modest barnacle.
Gelidium pusillum is a black mat growing in between barnacles.
0608219: a crusting red seaweed looking like black goo. Gelidium pusillum (1-2cm) is a brown to black mat growing in between barnacles.
f032332: rubberweed (Apophlaea lyallii?) feels like rubber elastic bands.
f051720: (Laurencia elata?)
moss weeds on a vertical wall
0703019: moss weeds on a vertical wall in relative shelter.

0703021: the moss weed (Gelidium caulacantheum?) from the photo on left. It feels like moss, dense and bouncy. compare size with the modest barnacles on right.
0703032: ?. Also which are the two limpets on left?
0703027: ? 
f051219: ? Champia sp.?
iridescent-blue red seaweed (Champia laingii)
f038114: the iridescent-blue red seaweed (Champia laingii) has stubby round branches and rounded endings.
f034114: the finely branched Pterocladia lucida branches in a flat plane. From this seaweed the agar gelatine is made. Agar is used as a stiffener in foodstuffs, toothpaste, soaps, shampoos etc. It is also used scientifically to grow bacteria on.

0910044: Pterocladia capillacea is a creeping alga with thin stems with tufted branches. It prefers to live under water. This seaweed is also suitable for making agar.
f051727: a  hard red seaweed growing out from a central clump (Apophlaea sinclairii).
finely branching  (Plocamium costatum)
f051729: finely branching  (Plocamium costatum) in the background. In the foreground Melanthalia abscissa?
f051725:  (Callophyllis variegata?).
f051728: ?
f051229: ?
fretsaw weed (Vidalia colensoi, Osmundaria c)
f051211: the fretsaw weed (Vidalia colensoi, Osmundaria c.) with alternating teeth is found in robust wave action. It does not feel slimy but rough and can grow to dense patches. North Island.
f051213: Laurencia thyrsifera?
f032523: Pterocladia pinnata?
f051215: Melanthalia abscissa?
0703037: Melanthalia abscissa? dichotomously branching flat, thin stems.
0703038: a fine, sparsely branching red seaweed found at spring low tide level.
f051204: a bushy red seaweed  (Rhodophyllis membranacea?)
Pachymenia lusoria
f222613: Pachymenia lusoria has long flat blades that look green, sprouting from thin stipes clustered from a single holdfast. Blades have jagged edges. West coast of the North Island and South Island but rare in central NZ.
f051507: a robust green looking leafy carrageen Gigartina circumcincta, growing flat in exposed conditions. The name carrageen comes from an edible Irish seaweed, the Irish moss.
f222610: . West Coast NI.
parsley weed (Gigartina alveata)
f222607: parsley weed (Gigartina alveata). West Coast NI and SI.
(Gigartina livida)
f222612: the small-leaved weed is a red seaweed (Gigartina livida) found on the West coast. The large fronds are ?
(Mesogloea intestinalis)
0609066: this hairy red seaweed feels like soft-cooked Italian pasta (Mesogloea intestinalis). It is found in extremely degraded and sheltered environments, such as inside harbours

a seaweed garden at the Poor Knights
f048222: a healthy seaweed garden at the Poor Knights islands shows a high variety of seaweeds against a backdrop of an Ecklonia kelp forest. From left to right: stalked kelp (Ecklonia radiata), hugged by strap kelp (Lessonia variegata) and beneath it pink paint. The red seaweeds are (Rhodophyllis membranacea?) and the broader leafed (?). The tall bladderweed looks like the featherweed (Carpophyllum plumosum) but is in fact (Cystophora platylobium). Such seaweed gardens can be found inside large rock pools.
an exposed South Island rock pool
f210512: an exposed South Island rock pool shows the dominant species. From left to right: the sheltered form of bullkelp (Durvillea antarctica), the long strings of giant kelp (Macrocystis pyrifera), the hardy cartilage weed (Xiphophora gladiata) and in the middle of the water the spiky-leafed (Echinothamnion sp.?).
f027103: a fine example of a semi-sheltered shore near Dunedin:  From left to right: the giant kelp (Macrocystis pyrifera)  with its thin leaves, the branching bullkelp (Durvillea willana), the hardy cartilage weed (Xiphophora gladiata) and the featherweed (Carpophyllum plumosum).