Taxonomy Order: Corallinales; Family: Corallinaceae. Etymology
Amphiroa, is Portuguese for ‘rock-hugging’, describing the algal habitat. Rigida, means ‘hard’ or ‘rigid’, and refers to the character of the calcified thallus. Description
The Amphiroa rigida is a hard, calcified alga, articulated, irregular and dichotomously branched. The dichotomous branching often occurs in the midst of a joint or at its edge. The joints are solid and maintain their shape, even after the alga has dehydrated. Size
The alga sometimes reaches several centimeters in length, usually 3 cm. The joints are 0.5 mm to 1 mm wide and double to five times that in length. Colour
Various shades of pink ranging from gentle to vivid. When dry, the alga turns white.
The alga is characterized by its pink colour and its coral-like shape. It is less tangled and populous than its neighbouring alga, corallina. In contrast to the Jania, its branches are jointed. They are also elongated and straight, as opposed to the triangular joints of the Corallina elongata. Habitat
The alga grows in deep water at depths of up to 80 m. It is usually found in the subtidal zone or in potholes. The Amphiroa rigida is mostly solitary and not found in large colonies. It does not come in contact with air. Individuals have been found in Egypt growing upon snail shells.
Biology and reproduction
The sexual reproductive organs and spores are arranged in special sex pods that are spread along the joints and