Padina Pavonica
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''Padina pavonica'', commonly known as the peacock's tail, is a small brown alga found in the
Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or approximately 20% of the water area of Earth#Surface, Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia (continent), ...
, the
Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
, the
Atlantic Ocean The Atlantic Ocean is the second largest of the world's five borders of the oceans, oceanic divisions, with an area of about . It covers approximately 17% of Earth#Surface, Earth's surface and about 24% of its water surface area. During the ...
and the
Mediterranean Sea The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern Eur ...
. It inhabits pools in the
littoral zone The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely flood ...
typically with clayey, silty or sandy sediments. Other habitats include rocks and shell fragments in the shallow sublittoral,
seagrass meadow A seagrass meadow or seagrass bed is an underwater ecosystem formed by seagrasses. Seagrasses are marine (saltwater) plants found in shallow coastal waters and in the brackish waters of estuaries. Seagrasses are flowering plants with stems and ...
s, mangrove roots and coral reefs on tidal flats.


Description

''Padina pavonica'' is a distinctive small brown alga growing to a diameter of up to . Young fronds are thin, leafy and flat, with entire margins. Older fronds are thicker, concave, fan-shaped or funnel-shaped, with lobed margins. The outer (under) surface has concentric rows of small, fine hairs and is banded with zones of olive green, pale and dark brown, while the inner (upper) surface is covered with a thin layer of slime. Both sides are thinly calcified and the margins tend to curl inwards. The blades are attached by a
holdfast Holdfast most often refers to: *Holdfast (biology), a root-like structure that anchors aquatic sessile organisms to their substrate *Holdfast (tool), a tool used to secure a workpiece to a workbench or anvil Holdfast or hold fast may also refer t ...
which may be matted.


Distribution and habitat

This seaweed has a wide distribution in the northeastern Atlantic Ocean, the Mediterranean Sea, the southern Atlantic Ocean, the Indian Ocean and the Pacific Ocean. The British Isles is its most northerly limit in the Atlantic Ocean, and it occurs on the south coast of Ireland, in Pembrokeshire and on the south coast of England. It grows in pools in the
littoral zone The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely flood ...
and in the shallow infralittoral zone. It typically grows where there are sandy, clayey or silty sediments in pools beneath receding
mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
and
sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...
cliffs. Other habitats include
mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...
roots, rocks, pieces of shell,
seagrass Seagrasses are the only flowering plants which grow in marine (ocean), marine environments. There are about 60 species of fully marine seagrasses which belong to four Family (biology), families (Posidoniaceae, Zosteraceae, Hydrocharitaceae and ...
meadows and
coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...
s on flats in the lower intertidal zone.


Ecology

The life cycle of this seaweed includes sexual reproduction and spore-producing
asexual reproduction Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the f ...
. In Britain the fronds die back in winter and the
rhizoid Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be un ...
s resprout in the early summer, producing new fronds. After about twenty days these are mature, long or more, and produce
tetraspore Tetraspores are red algae spores produced by the tetrasporophytic (diploid) phase in the life history of algae in the Rhodophyta as a result of meiosis.Jones, W.E. Revised and reprinted 1964. A Key to the genera of the British seaweeds.''Field S ...
s in concentric rings a millimetre or so wide. By the time the frond reaches a length of it will have produced six to twelve generations of tetraspores. In Britain, plants seem to reproduce entirely asexually but in other parts of the seaweed's range, plants can be either male or female and produce
gametophyte A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the se ...
s which release
gamete A gamete ( ) is a Ploidy#Haploid and monoploid, haploid cell that fuses with another haploid cell during fertilization in organisms that Sexual reproduction, reproduce sexually. Gametes are an organism's reproductive cells, also referred to as s ...
s into the sea.


Human Uses

Extracts of this seaweed have been found to have
anticarcinogen An anticarcinogen (also known as a carcinopreventive agent) is a substance that counteracts the effects of a carcinogen or inhibits the development of cancer. Anticarcinogens are different from anticarcinoma agents (also known as anticancer or ant ...
ic and
cytotoxic Cytotoxicity is the quality of being toxic to cells. Examples of toxic agents are toxic metals, toxic chemicals, microbe neurotoxins, radiation particles and even specific neurotransmitters when the system is out of balance. Also some types of dr ...
activity. For example, an organic extract shows toxicity to the oral epidermoid carcinoma cell line KB with a minimal infective dose of 6.5 μg/ml. A
benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...
extract of the seaweed has been shown to be effective in controlling the red cotton stainer (''
Dysdercus cingulatus ''Dysdercus cingulatus'' is a species of Hemiptera, true bug in the family Pyrrhocoridae, commonly known as the red cotton stainer. It is a serious Pest (organism), pest of cotton crops, the adults and older nymphs feeding on the emerging bolls a ...
''), a pest of cotton crops, killing both eggs and
nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...
.


References

{{Taxonbar, from=Q512653 Protists described in 1753 Dictyotaceae Brown algae species