Halosaccion glandiforme is a saccate alga with a short stipe and discoid holdfast. It is commonly referred to as the “sea sac.” It has a relatively thin thallus that forms an ellipsoidal, seawater-filled structure.
Its coloring can range from greenish-brown to reddish purple. Over the course of a year, it will typically grow to a length of 10-20cm (Johnson 1994).
One of the more interesting quirks of the morphology of H. glandiforme is that its sac-like structures possess approximately 5-15 pores located towards the distal end (Vogel & Loudon 1985). When the sac is full of water and is physically compressed, several streams of water will go shooting outwards which, while not a common occurrence when H. glandiforme is left to its own devices, is nonetheless highly entertaining to watch.
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Microscopic view showing inner surface of thallus.
References
Johnson LE. 1994. Enhanced settlement on microtopographical high points by the intertidal red alga Halosaccion glandiforme. Limnology and Oceanography. 39: 1893-1902.
Vogel, S and C Loudon. 1985. Fluid mechanics of the thallus of an intertidal red alga, Halosaccion glandiforme. The Biological Bulletin. 168: 161-174.
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