An educational resource dedicated mainly to the photography
and diversity of marine life that can be found in coastal waters
and intertidal areas of Great Britain and Ireland by David Fenwick.

Seaweed galls and their causative agents (Algal gall images)
Galls caused by marine nematodes / eelworms

Rhabditida (Order) > Tylenchina (Suborder) > Tylenchomorpha (Infraorder) > Sphaerularioidea (Superfamily) > Anguinidae (Family)

Halenchus dumnonicus Coles, 1958.
A nematode gall on Fucus vesiculosus,
Bladder Wrack.

Halenchus fucicola (de Man, 1892) Cobb, 1933.
A nematode gall on Ascophyllum nodosum,
Knotted or Egg Wrack

Galls caused by copepods (crustacea)

Copepoda (Subclass) > Neocopepoda (Infraclass) > Podoplea (Superorder) > Harpacticoida (Order) > Thalestridae (Family) > Thalestrinae (Subfamily)

Galls possibly caused by Thalestris rhodymeniae (Brady, 1894) copepod nauplius in Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 from Mousehole, Cornwall, 16.04.18.

The following may be an early stage in gall development.
Palmaria palmata, Dulse, galled by unknown
agent, Penzance, Cornwall, 25.08.18.

Galls caused by algae

Dilsea carnosa, Red Rags or False Dulse, galled by unknown alga, Streblonema? - Skilly, Cornwall, 24.04.20.

Himanthalia elongata, Thong Weed, thallus gall possibly
caused by an alga. Penzance, Cornwall, 09.05.20.

Laminaria digitata, Oarweed, stipe possibly galled by a brown alga, Skilly, Newlyn, Cornwall, 08.09.18.

Galls likely caused by fungi

Halidrys siliquosa, Sea Oak, galled by Haloguignardia sp. of fungi? Hannafore, Cornwall, 30.03.17 and 27.10.11.

Galls with un-identified agents

Ascophyllum nodosum, Knotted / Egg Wrack, galled
by unknown agent, Perranporth, Cornwall, 30.01.15.

Chorda filum, Dead Man's Rope / Sea Lace, Chorda filum,
galled / distorted / spiralled growth, unknown agent.

Laminaria digitata, Oarweed, frond base galled by unknown agent, Battery Rocks, Penzance, 31.10.16.

Saccorhiza polyschides, Furbelows, galled by unknown agent, Newlyn, 17.03.17.

For mines in algae see -

Dactylopusioides macrolabris (Claus, 1866)
- Copepod mining the brown algae Dictyota dichotoma

Diarthrodes feldmanni Bocquet, 1953
- Copepod mining the red algae Cryptopleura ramosa

Seaweed Algal Galls and their causative agents fungi bacteria virus nematode images UK