Rhodophyta, Red Algae

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Laurencia papillosa (C. Agardh) Greville

Rhodophyta, Order: Ceramiales; Family: Rhodomelaceae.

Etymology

Laurencia, the genus is named after the French scientist

M. de la Laurencia. Papilla means ‘nippled’, and describes the nipples that may be found all over the plant. Description

The Laurencia papillosa is a cartilaginous alga, erect and inflexible, very common on abrasion platforms in the intertidal zone. Its central axis and its side axis are covered with many, dense nipples.

Size

The alga usually reaches a height of 10 cm, and sometimes more. The nipples range in size from 1 to 3 mm, as does the central axis.

Colour

The Laurencia papillosa appears in shades of green, brownish-green or crimson-green, all in accordance with light conditions, as is the case with many other species of algae.

Special features

The species is very common and easy to identify thanks to its solid structure and nipples. Many individuals can be found covered with epiphytic Jania rubens. Often, the thallus will have been nibbled to its base, probably by fish.

Habitat

The Laurencia papillosa is very common along rocky coasts or abrasion platforms, sometimes also in the upper regions of potholes.

Biology and reproduction

The life cycle is three-staged. Reproductive spores, tetraspores, are carried upon the edge of the nipples and can be seen through a magnifying glass as dark dots. Many epiphytic species settle upon the Laurencia papillosa, possibly because of the rigidity of its thallus.

Research shows Laurencia papillosa secretion contains ingredients that are poisonous to fish, a quality that does not clearly assist the alga in this region, since many individuals have been found to be eaten away.

Seasonality and distribution

The alga can be found throughout the year, especially in summer and autumn. Many individuals found in the field are covered with Jania rubens. The species is globally distributed and common in the Mediterranean, the Atlantic Ocean, the Indian Ocean and the Pacific Ocean.

The genus includes dozens of species that are common in warm, temperate and even cold seas. The shape of the holdfast is consequential in defining the species and so, when collecting individuals, it is important to secure the holdfast as well. The Laurencia obtusa species is also represented in the area, but it is not as common (see below). Some claim that the Laurencia pyramidalis is actually a sub-species of the Laurencia papillosa. Other species in this region include:

Laurencia microcladia  Kutzing 

Laurencia paniculata (C. Agardh) J. Agardh

Laurencia pinnatifida (Hudson) Lamouroux

Laurencia pyramidalis Bory and  Kutzing 

Laurnecia perforata Montagne.

 

Laurencia papillosa  - nipples arrangement on the thallus. Research carried out in Jordan on individuals collected in the Red Sea show that two species, the Laurencia papillosa and Laurencia obtusa, have economic value for agar manufacture.

The alga is served in Scotland, the Philippines and other Pacific Ocean islands. In Hawaii, one must ask for Limu Lipeepee. The Laurencia papillosa is one of the only algae with a name in spoken Arabic: Arlut.

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