Rouphael and Abdulla, (2011). Field guide of seagrasses of the red sea. IUCN, Gland, Switzerland and Total Foundation, Courbevoie, France

Halophila decipiens

Halophila ovata

Cytoplasmic strand

Microscopic image of leaf tip

Line digraram of H. ovalis

Seagrass can reproduce through sexual or asexual methods. Seagrasses have flowers and pollination systems that are well adapted for pollination by water. Seagrass form tiny flowers, fruits and seeds. Most seagrass species produce flowers of a single sex on each individual, so there are separate male and female plants. In most species, flowers are small, white and are borne at the base of the leaf clusters. The stamens (male part) and pistils (female part) extend above the petals to assist pollen release and pollination respectively.

Seagrass pollen grains are elongated into a filamentous shape. The filamentous nature of pollen grains helps transport within water. Halophila and Thalassia have spherical pollen grians, but they remain joined together in long chains giving the same effects as having elongated, filamentous pollen grains.

Pollen is a threadlike structure about 2 mm long which adheres to a water-insoluble matrix on the receptive female stigma to achieve fertilization. The mechanisms by which this thread of pollen reaches a flower constitute exquisite adaptations to the marine environment.

Vectors: hydrophilic pollination  

Growing season is September-November. Spoon seagrass has separate male and female plants. The flowers form at the base of the shoot but may extend to above the height of the leaves. The male flower remains low. The round fruits are tiny.

Flowers:- solitary, axillary, covered by two spathes.

Perianth:-Tepals 3, broad elliptic

Ovary:- Ellipsoid in shape, 1-celled with pointed apex

Fruit:- Ovoid to ellipsoid with 18-27 seeds, 3-4 mm long with 3 mm long rostrum

Seeds:- Globose, white in color when young but brown when mature. Seeds are numerous, ovoid with finely reticulate testa.

Flowering and Fruiting : Troughout the year

The response of seagrass propagules to waves and currents at a location will depend largely on the physical properties (especially buoyancy) of the seed, fruit, or vegetative bract (spathe) that surrounds the seeds. Seagrass propagules are produced as two basic forms: positively buoyant (floating) fruit, spathe, and viviparous seedlings and neutrally or negatively buoyant seeds and viviparous seedlings. The seeds of seagrasses are generally neutrally or negatively buoyant, because they must settle on the substrate at considerable depth. However, seeds can be retained within positively buoyant structures such as fruits or spathes or can germinate as viviparous seedlings. All of these structures eventually sink, sometimes after being transported considerable distances

Maximum length of leave : 4 - 12.6 cm

Maximum length of petiols : 1 -8.2 cm

Cross veins : 13 - 20 pairs

Male flower : up to 4 cm

Female flower : 2 - 5.3 cm

• Blade or subulate leaves with sheaths, fitted for high-energy environments.
• Hydrophilous pollination, allowing submarine pollination and subsequent propagule dispersal.
• Extensive lacunar systems allowing the internal gas flow needed to maintain the oxygen supply required by their below-ground structures in anoxic sediments. Seagrass species are all clonal, rhizomatous plants, a necessary adaptation for angiosperm growth in the high-energy marine environment
• Halophila ovalis is rapidly growing, with high turn-over, wide ecological range, and is considered a pioneering species. In Arabian Gulf, this species tolerates extreme conditions with salinity varying from 38-70 practical salinity units (psu) and temperatures of 10-39°C (inshore) and 19-33°C (offshore).
  Photosynthetic studies in Tanzania indicate an enhanced photosynthetic rate in the high, frequently air-exposed, inter tidal zone which may have been related to a capacity to take up the elevated HCO₃ levels directly. This is a pioneer species in Mozambique in exposed sandy areas close to the coastline
• It grows rapidly and survives well in unstable and depositional environments in eastern Australia
• It is widely distributed in Thailand because of its ability to grow in different habitats, such as mud, muddy sand and dead coral fragments in the upper littoral and sub tidal areas.
• In Peninsular Malaysia, it is common all around the coast on muddy shores and areas exposed at low tide. This species is ephemeral with rapid turn-over and high seed set and is well adapted to high levels of disturbance.
• The epidermal cells of some species of Halophila, including H. ovalis, are reported to possess an unusual double membrane structure or annulus which may be involved in osmoregulation.

calorific values : Leaves - 28.08 K Cal g^-1 and Rhizomes - 37.03 K Cal g^-1

This species is common & widespread. It is impacted by anthropogenic threats locally, but recovers quickly if the threats are removed.  Its global population trend is stable or increasing.

H. ovalis is more susceptible to elevated temperatures than some species of seagrass. Climate change is also a threat for this species, and it is collected and sold internationally for aquaria.

Oil globules and oily black films discharges negatively affect H. ovalis in the Arabian Gulf, and overexploitation and influences from activities on land (trawling activities, high hotel density in close proximity to the beach, raking, burying and removing seagrass beach cast material) occur in Kenyan and Tanzanian shores. Declining water quality due to increasing populations in coastal towns and cities is also an issue.

In India, the natural causes of destruction are cyclones, waves, intense grazing and infestation of fungi and epiphytes, as well as "die-back" disease. Other threats include anthropogenic activities such as deforestation in the hinterland or mangrove destruction, construction of harbours or jetties, and loading and unloading of construction materials. Anchoring and moving of boats, ships, dredging and discharge of sediments, land filling and untreated sewage disposal.
In Western Australia, threats include human activities such as direct physical damage caused by port and industrial development, pipelines, communication cables, mining and dredging, excessive loads of nutrients causing seagrass overgrowth and smothering by epiphytes, and land based activity associated with ports, industry, aquaculture, farming, direct physical damage by recreational and commercial boating activities.

In eastern Australia, population reduction is caused by the result of light reduction due to sediment loads in water, coastal development, dredging and marine developments, and minor damage from boating and shipping activities. This species also could be impacted by coastal runoff and to some extent trawling activities.
In Thailand, it is threatened by a combination of illegal fisheries and fishing practices, and land-based activities, especially mining, reduced water quality resulting from upland clearing, development along rivers and destruction of mangrove forests.

In Malaysia, loss was caused by intensive sand mining for reclamation activities in mangrove swamps as part of the construction of a condominium which resulted to suspended particles in the water settled on its leaves, blocking sunlight for photosynthesis and causing considerable stress and mortality through burial. This species also was damaged by intense winds, waves and sediment movement during the northeast monsoon storms of October 1998 to January 1999.

In the western Pacific, threats include coastal development, dredging, and marina developments, climate change and associated increase in storm activity, water temperature and/or sea-level rise.

In Indonesia, H. ovalis is threatened mainly by physical degradation such as mangrove cutting and coral reef damage, by marine pollution from both land- and marine-based resources, and by over exploitation of living marine resources such as fish, molluscs and sea cucumbers.
In the Philippines, it is threatened by eutrophication, siltation, pollution, dredging and unsustainable fishing methods.

In Japan, threats occur from industrial developments in coastal regions, land reclamation resulting to loss of vegetation, water pollution, disturbance of habitats by fish trawling, changes in environmental conditions due to human activities.

H. ovalis as indicator species, which can be considered as a pioneer community in the intertidal zone.

Up to 79 m depth

The plant occurs around reefs, estuaries, islands, inter-tidal areas, on soft sand or mud substrates. It is often found in meadows that dominate a sand bank or other patch of sea floor.

Lakshaadweep Islands,West Bengal, Orissa, Andhra Pradesh,Tamilnadu, Andaman and Nicobar Islands, Gujarat, Goa

Under water view of Halophila ovalis

In this movie you can see the transport of chloroplasts over a cytoplasmatic strand.

In this movie you can see the transport of chloroplasts over a cytoplasmatic strand.

The distribution range of H. ovalis as per IUCN status

In Southeast Asia, especially in the Philippines, seagrasses are used in all kinds of ways. They are woven into baskets, used to thatch roofs, stuffed into mattresses and used a fertilizer.

Seagrasses can improve water quality. Fast moving water stirs up the sediment on the bottom, which makes the water cloudy. When flowing water hits seagrass, it slows down allowing particles to settle. Seagrasses can also help by acting like a filter if there are too many nutrients in the water or sediment

In India, coastal indigenous people claim that their ancestors have used seagrasses for thousands of years for a variety of uses from food to medicine.

A handful of H.Ovalis leaves is toasted with three drops of sesame oil and consumed for three days to treat iron deficiency. A leaf paste is mixed with turmeric and applied to cure various skin ailments, including burns and boils.

Environmental ranges

This is a common species. Its global population trend is stable or increasing as it can tolerate disturbances.

Primary Producers

Antimicrobial activity 

Bidentate - Having two teeth or tooth like parts.

Blade – A blade is a narrow, flat leaf.

Blunt - Having a dull edge or end; not sharp.

Branched root - A secondary root or limb growing from the trunk or main root of a tree or shrub or from another secondary limb

Broadly acute - Sharply pointed; converging edges making an angle of less than 90°.

Cross veins – A transverse vein that connects adjacent longitudinal veins in the wing of an insect

Flower – The flower is the reproductive unit of angiosperms. Flowers usually have carpels, petals, sepals, and stamens.

Fruit – That structure which bears the seeds

Lamina - The lamina is the blade of a leaf

Lanceolate - Lanceolate leaves are shaped like a lance; they have a broad base and taper to a point

Lateral teeth - With minute teeth on margin of leaf.

Leaf hairs - Row of cells borne on the surface of an organ

Leaf margin - Lateral means of, near, or from the side of an organism.

Leaf tip - The edge, as in the edge of a leaf blade.

Long Oval - Shaped like a section through the long-axis of an egg and attached by the wider end.

Longitudinal veins - A leaf with longitudinal striate venation has its veins arranged almost parallel to one another, running the length of the leaf

Oval - Planar, shaped like a flattened circle, symmetrical about both the long and the short axis; about twice as long as broad, tapering equally both to the tip and the base; oval.

Ovate - Broad and rounded at the base and tapering toward the end.

Pointed - Having an end coming to a point or sharp.

Pollen – Pollen is the male reproductive cell of flowering plants and cone-bearing plants. Pollen grains are produced in the anther of a flower.

Pollination - Pollination is the transfer of pollen from the anther to the stigma.

Propagule – A vegetative structure that can become detached from a plant and give rise to a new plant, e.g. a bud, sucker, or spore

Rhizome – A perennial underground stem usually growing horizontally.

Root - A unit of a plant's axial system which is usually underground, does not bear leaves, tends to grow downwards, and is typically derived from the radicle of the embryo.

Rounded - Shaped into the form of a circle or sphere; made round.

Seed – The seed is the reproductive unit of some plants

Seedlings – A young plant, especially one raised from seed and not from a cutting

Serrulate - Having a minutely serrate margin, as in a leaflet of the rose.

Sheathed leaf base - The leaf base when it forms a vertical coating surrounding the stem (a tubular or rolled part of an organ, e.g. the lower part of the leaf in most grasses.)

Sickle - Curved like shape

Spathe – A large sheathing bract enclosing the flower cluster of certain plants, especially the spadix of arums and palms

Stigma – The stigma is part of the pistil, the female reproductive tissue of a flower. The stigma receives the male pollen grains during fertilization

Tubular - The form of a tube or cylinder.

Viviparous – Germinating while still on the plant, as certain bulbs and transformations of floral tissues.