Bladder wrack (Fucus vesiculosus)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Chromista · Phylum: Ochrophyta · Class: Phaeophyceae · Order: Fucales · Family: Fucaceae · Genus: Fucus.

Accepted name: Fucus vesiculosus · Authority: Linnaeus, 1753 · Taxonomic status: accepted · AphiaID: 145548.

Synonyms and superseded combinations recorded for this taxon: Fucus axillaris f. balticus (C.Agardh) Kjellman, 1880; Fucus axillaris var. subecostatus J.Agardh, 1868; Fucus balticus C.Agardh, 1814; Fucus divaricatus Linnaeus, 1753; Fucus excisus Forsskål, 1775; Fucus inflatus Linnaeus, 1753; Fucus vesiculosus f. abbreviatus Kjellman, 1890; Fucus vesiculosus f. acutus Lyngbye, 1819; Fucus vesiculosus f. angustifolius (C.Agardh) Kjellman, 1890; Fucus vesiculosus f. angustifrons (Gobi) Kjellman, 1890; Fucus vesiculosus f. angustifrons Gobi, 1878; Fucus vesiculosus f. balticus (C.Agardh) Dannenberg, 1927; Fucus vesiculosus f. balticus Levring, 1940; Fucus vesiculosus f. crispus Kjellman, 1890; Fucus vesiculosus f. elongatus Kjellman, 1890; Fucus vesiculosus f. filiformis (C.Agardh) Kjellman, 1890; Fucus vesiculosus f. flabellatus Kjellman, 1890; Fucus vesiculosus f. fluviatilis Kjellman, 1890; Fucus vesiculosus f. lanceolatus Kjellman, 1890; Fucus vesiculosus f. latus Kjellman, 1890; Fucus vesiculosus f. limicola F.S.Collins, 1906; Fucus vesiculosus f. nanus (C.Agardh) Kjellman, 1890; Fucus vesiculosus f. plicatus Kjellman, 1890; Fucus vesiculosus f. pseudoceranoides (Areschoug) Kleen, 1874; Fucus vesiculosus f. racemosus Kjellman, 1890.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=145548 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (SeaLifeBase)

Measured values published by SeaLifeBase for Fucus vesiculosus. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Habitat zone: sessile.

SeaLifeBase notes: Thrives in moderate to low eutrophicated systems. Provides food and shelter for bivalves such as Idotea baltica , Gammarus oceanicus and Palaemon adspersus (Ref. 95891).

Source: SeaLifeBase species summary (SpecCode 117527) — https://www.sealifebase.se/summary/Fucus-vesiculosus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

124,823 georeferenced occurrence records for Fucus vesiculosus are published through GBIF from 37 countries or marine areas. The map above plots 238 distinct locations from a sample of 3,000 records, omitting 299 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Sweden (43,004); United Kingdom of Great Britain and Northern Ireland (19,547); Norway (14,770); Finland (14,164); Estonia (9,391).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 8222574) — https://www.gbif.org/occurrence/search?taxon_key=8222574&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=145548 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

The fronds of F. vesiculosus grow to 150 cm long and 2.5 cm wide and have a prominent midrib throughout. It is typically attached by a basal disc-shaped holdfast but can also be unattached. It has almost spherical air bladders, which are usually paired one on either side of the mid-rib but may be absent in young plants. The margin is smooth and the frond is dichotomously branched. It is sometimes confused with Fucus spiralis with which it hybridises and is similar to Fucus serratus.

Plants of F. vesiculosus are dioecious. Gametes are generally released into the seawater under calm conditions, and the eggs are fertilized externally to produce a zygote. Eggs are fertilized shortly after being released from the receptacle. A study on the coast of Maine showed that there was 100% fertilization at both exposed and sheltered sites. Continuously submerged populations in the Baltic Sea are very responsive to turbulent conditions. High fertilization success is achieved because the gametes are released only when water velocities are low.

Individuals of F. vesiculosus from the North Sea colonized the Baltic Sea less than 8,000 years ago. The event is paralleled by a switch from what seems to be obligate sexual recruitment to facultative asexual recruitment. Asexual reproduction in Baltic Sea populations is accomplished by the production of adventitious branches that come loose and reattach to the bottom by the formation of rhizoids. Asexual reproduction is also important for maintaining unattached populations. Adventitious branches are present in thalli of F. vesiculosus in other areas too but asexual formation of new thalli has never been reported outside the Baltic Sea.

Fucus vesiculosus is a common large brown alga on the shores of the British Isles. It has been recorded from the Atlantic shores of Europe, Northern Russia, the Baltic Sea, Greenland, Azores, Canary Islands, Morocco and Madeira. It is also found on the Atlantic coast of North America from Ellesmere Island, Hudson Bay to North Carolina.

The species is especially common on sheltered shores from the middle littoral to lower intertidal levels. It is rare on exposed shores, where any specimens may be short, stunted and without the air vesicles. F. vesiculosus supports few colonial organisms but provides a canopy and shelter for the tube worm Spirorbis spirorbis, herbivorous isopods such as Idotea and surface-grazing snails such as Littorina obtusata. Phlorotannins in Fucus vesiculosus act as chemical defenses against the marine herbivorous snail Littorina littorea, while galactolipids act as herbivore deterrents against the sea urchin Arbacia punctulata. Methyl jasmonate may induce the phlorotannins production. Fucophlorethol A is a type of phlorotannin found in F. vesiculosus.

Fucus vesiculosus can be cooked and eaten.

It was the original source of iodine, discovered in 1811, and was used extensively to treat goitre, a swelling of the thyroid gland related to iodine deficiency.

It is also sold as a nutritional supplement. Primary chemical constituents include mucilage, algin, mannitol, fucitol, beta-carotene, zeaxanthin, volatile oils, iodine, bromine, potassium and other minerals.

Consumption of F. vesiculosus can cause platelet inhibition, which may potentiate the anticoagulant activity of warfarin (Coumadin). It should be avoided before surgery.

Some people may suffer an allergic reaction to the iodine in F. vesiculosus.

Source: Wikipedia: Fucus vesiculosus — https://en.wikipedia.org/wiki/Fucus_vesiculosus (CC BY-SA 4.0). Accessed 2026-09-23.