Pardachirus marmoratus

Finless sole
Finless sole, Pardachirus marmoratus
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Pleuronectiformes
Family:	Soleidae
Genus:	Pardachirus
Species:	P. marmoratus
Binomial name
Pardachirus marmoratus (Lacépède, 1802)
Synonyms
Achirus marmoratus Lacepède, 1802 Achirus barbatus Lacepède, 1802 Achirus punctatus Desjardins, 1837

Pardachirus marmoratus, also known as the finless sole, the speckled sole or the Red Sea Moses sole,^[1] is a small fish from the Red Sea that secretes an ichthyotoxic milky substance from the base of its dorsal and cloacal fins. This secretion contains pardaxin, a lipophillic peptide that causes severe plasma membrane disruption resulting in cell leakage. The pardaxin containing secretion is used as a defensive mechanism against predators including sharks. Pardaxin is irritating to predator fish, particularly affecting the sensitive gills. Dr. Eugenie Clark conducted much of the early work on Pardachirus marmoratus.^[2]

The adult finless soles are bilaterally symmetrical and as they mature their left eye migrates on to the right side of the head. The highly compressed body is convex on the eyed side and flat on the blind side. The rounded caudal fin is not attached to either the dorsal or cloacal fin. It is variable in colour frequently whitish, pale brown to pale grey with a scattering of irregular dark brown ring shape markings and many dark brown spots on the head, body, and fins. long the lateral line, there are normally two brown dots containing yellow flecks.^[3]

There is much biotechnological interest in pardaxin, early interest focused on potential shark repellent applications while newer research focuses on antimicrobial and neurotoxic potential of pardaxin and its analogues.^[2] One toxin produced, pardaxin-1, does have unusual shark repellent and surfactant properties it created voltage-dependent, ion-permeable channels in membranes and at high concentration it causes lysis in cell membranes. This toxin has been demonstrated to be 5-10 times more toxic, cytolytic and active in the formation of pores in cell membranes than the other toxin exuded, pardaxin-2.^[4]

This species is found in shallow, coastal waters where the seabed consists of sand or mud,^[1] often near coral reefs,^[3] and they feed mainly on benthic invertebrates. It is caught for consumption, despite the poison it exudes and is marketed fresh.^[1] They often spend the day buried in the sand with only its eyes and nostrils visible.^[3]

It is found in the western Indian Ocean from the Red Sea to Sri Lanka and along the east coast of Africa to Durban.^[1]

According to the legend, when Moses parted the waters of the Red Sea so that the Israelites could flee from the Egyptians, a small fish was caught in the middle and split in two; the halves become flatfish-and are known to this day as Moses soles.^{[citation needed]}

But the truth about the Moses soles(Pardachirus marmoratus), which flourishes in the Gulf if Aqaba between the Sinai Peninsula and Saudi Arabia, is much stranger. In self-defense this little fish secretes a milky substance that is lethal to other sea creatures. The poison, paradaxin, is produced in glands along its rear fins.^{[citation needed]}

Scientists have found that just one part of paradaxin in 5,000 parts of seawater is enough to kill mollusks, sea urchin, and small fish. When a group of researchers placed a Moses soles into a pool with two white-tip sharks, the sharks made a dive for the fish and then retreated, their jaws agape as if the sharks were unable to close them. Because it enters the shark's bloodstream and causes paralysis, paradaxin seems to be the ideal shark repellent.^{[citation needed]}

Common Power[]

In theory paradaxin could be used by divers as the protection against sharks. But not only are there not enough soles to provide the poison in required quantity, its chemistry is too complex to produce artificially. However, researchers have found that paradaxin lowers surface tension of water, just as household detergent does. Additional tests indicate that some common detergents scare off sharks as effectively as paradaxin.^{[citation needed]}

If this theory proves reliable, possibly in the future divers in shark-infested waters will arm themselves with a bottle of dishwashing detergent.^{[citation needed]}

References[]

External links[]

• Photos of Pardachirus marmoratus on Sealife Collection