The Exotics Guide

Sargassum muticum Key Image

Sargassum muticum from San Francisco Bay.

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Sargassum muticum (Yendo, 1907)

JAPANESE WIREWEED

  • Kingdom: Plantae
  • Division: Phaeophycophyta
  • Class: Phaeophyceae
  • Order: Fucales
  • Family: Sargassaceae

Sargassum muticum is a large, yellowish-brown or olive-brown seaweed that can be distinguished from most other Pacific coast seaweeds by its small, spherical float bladders. It grows on rocks, shells or other hard objects, attached by a stout, spongy holdfast. The lowest part of the stalk just above the holdfast is sometimes divided into a few main stems, and gives off several flat, blade-like leaves up to 10 cm long.

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Cryptosula pallasiana Image 6

Microscope detail of a Cryptosula pallasiana colony in San Francisco Bay.

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5

Microscope detail of a Cryptosula pallasiana colony from San Francisco Bay. Note the rounded rectangular outline of the aperture, with slight indents on the sides; and the large pores perforating the upper surface of the zooecium.

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4

Detail of another Cryptosula pallasiana colony in San Francisco Bay.

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Cryptosula Key Image

Detail of a Cryptosula pallasiana colony in San Francisco Bay.

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Cryptosula pallasiana b

Cryptosula pallasiana on a floating dock in San Francisco Bay, with an anemone (Diadumene sp.) growing on it at upper right. Even at this scale, Cryptosula’s large apertures are clearly visible.

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Cryptosula pallasiana Image 1

A Cryptosula pallasiana colony on the underside of an intertidal rock in San Francisco Bay, partly overgrown by an orange bryozoan (Schizoporella unicornis) at lower right.

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Cryptosula pallasiana (Moll, 1803)

  • Kingdom: Animalia
  • Phylum: Bryozoa
  • Class: Gymnolaemata
  • Order: Cheilostomata
  • Suborder: Ascophora
  • Family: Cryptosulidae

Cryptosula pallasiana is a colonial animal that grows in flat, encrusting sheets on a variety of substrates including shells, rocks, wood, glass, plastic, cement, seaweeds, sea grasses and solitary sea squirts. On flat surfaces the colonies may be more or less round and several centimeters across. In Florida, the edges of some colonies are raised in frills.

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Carcinus maenas Image 8

A poster used to track the spread of Carcinus maenas on the Pacific Coast.

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