Acetabularia major (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit; 2, apices of rays; 3, corona inferior, front view; 4, corona superior, front view; 5, coronae in transverse section.

Acetabularia major G. Martens

Protologue: Preuss. Exped. Ost-As., Tange: 25, pl. 4, fig. 3 (1868).

Family: Polyphysaceae

Chromosome number: 2n= unknown

Synonyms

• Acetabularia crenulata J.V. Lamour. var. major Sond. (1871),
• A. denudata Zanardini (1878),
• A. gigas Solms (1895).

Vernacular names

• Mermaid's wine glass (En)
• Indonesia: gembur batu, keji beling, pecah beling (Javanese, Sundanese)
• Philippines: payong-payong.

Origin and geographic distribution

A. major is found in the Indian Ocean from Sri Lanka and in the Pacific Ocean from Melanesia, Taiwan and islands in the Torres Strait. In South-East Asia it is known from Thailand (Gulf), Peninsular Malaysia, Indonesia (West Java, Timor, Irian Jaya) and the Philippines.

Uses

A. major is used on the northern coast of Java as a medicine against stones in the gall-bladder, in the kidney or in the urine bladder. This is probably due to the ability of the rhizoids of the alga to secrete acids. In Indonesia (mainly West Java), A. major is also used as a laxative. Other Acetabularia spp. may also be used in the same way. Some of the unicellular, uninucleate green algae of the genus Acetabularia J.V. Lamour. have been used extensively for research in morphogenetics, physiology, molecular biology and cell biology.

Production and international trade

A. major is not harvested or cultivated for commercial use. It is, however, possible to raise it in laboratory culture.

Properties

CaCO₃ is present in A. major in the form of aragonite (orthorhombic). No research has yet been done on the role of this alga in destroying intestinal stones. The vegetative cell walls of A. major partially consist of crystalline mannan as the skeletal component, but the gametangial cysts have cellulosic walls.

Description

• Thalli erect, moderately calcified, stalk slender, 2-20 cm tall, cap 10-20 mm in diameter, made up of 63-83 long slender rays, joined by calcification; tip of each ray ending in an entire, slightly emarginate or somewhat rounded margin; side walls with notches, giving them a streaky pattern.
• Corona superior (inside the cap) with segments 230-250 μm long, bearing (6-)8(-9) hair scars, often arranged in uniseriate rows; corona inferior (below the cap) with segments 265-280 μm long, ending in a rounded, truncate or emarginate margin.
• Life cycle diplontic.
• Gametangial cysts inside the cap rays oval, 119-129 μm × 89-109 μm, or spherical, 98-115 μm in diameter. Each cap ray containing about 100 cysts.

Growth and development

The adult form of the perennial thalli of A. major is composed of three portions: rhizoid, stalk and cap. Following conjugation of the haploid isogametes, the zygote (50 μm) gives rise to a rhizoid, which contains a single large nucleus, and an elongating stalk which ultimately terminates its growth (after 3-4 months) by the differentiation of a species-specific cap (about 1 cm in diameter) at the tip. At maturity the cap is subdivided into many rays, each of which is functionally a gametangium. At this time the large (150 μm) nucleus divides by mitosis into thousands of secondary nuclei. The nuclei migrate through the stalk into the rays of the cap where they form cysts. The cysts are set free when the cap degenerates and ultimately give rise, after meiosis of each secondary nucleus and many mitotic divisions, to numerous motile isogametes.

Other botanical information

A. major is the largest species in Acetabularia. A. major var. gigas Solms (syn. A. gigas) is up to 25 cm long. The cap of this variety is composed of 70-80 sporangial rays and can reach a diameter of 30 mm. The corona superior is 300-400 μm long, while each segment bears 8-10 hair scars.

Ecology

A. major is usually solitary and grows on hard objects like dead coral on moderately wave-washed habitats near shore, on hard substrates in sheltered sand flats with seagrasses and between large seagrasses. The very large specimens of var. gigas have never been found in their natural habitat, but only washed ashore.

Propagation and planting

A. major is not grown in phycoculture.

Phycoculture

A. major, being a single-celled marine alga containing one nucleus, is capable of completing its life cycle in laboratory culture within 4-5 months, while in nature it takes at least a year.

Harvesting

A. major is collected by hand.

Handling after harvest

A. major can be sun-dried.

Prospects

A. major will probably remain a traditional medicine in Java. It has to be tested for effectiveness. The thin calcareous tubes formed by this alga might be suitable for use in surgery, as a temporary substitute for skeletal elements, etc.

Literature

• Berger, S. & Kaever, M.J., 1992. Dasycladales: an illustrated monograph of a fascinating algal order. Georg Thieme Verlag, Stuttgart, Germany. 247 pp.
• Mariscal, R.N., 1974. Experimental marine biology. Academic Press, New York, United States. pp. 316-317.
• Trono Jr, G.C. & Santiago, A.E., 1978. Notes on the genus Acetabularia (Chlorophyta) in the Philippines. Kalikasan 7(1): 77-90.
• Valet, G., 1969. Contribution à l'étude de Dasycladales, 2. Cytologie et réproduction, 3. Révision systématique [Contribution to the study of Dasycladales, 2. Cytology and reproduction, 3. Systematic revision]. Nova Hedwigia 17: 551-644.

Sources of illustration

Trono, G.C., 1986. Philippine seaweeds. In: Guide to Philippine flora and fauna. Vol. 1. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines. Goodwill Bookstore, Manila, The Philippines. Fig. 47, p. 243. Redrawn and adapted by P. Verheij-Hayes.

Authors

• P.Y. van Aalderen-Zen