''Pardachirus marmoratus'', the finless sole, speckled sole or Red Sea Moses sole, is a species of

flatfish A flatfish is a member of the Ray-finned fish, ray-finned demersal fish Order (biology), suborder Pleuronectoidei, also called the Heterosomata. In many species, both eyes lie on one side of the head, one or the other migrating through or around ...

native to the western Indian Ocean.

Description

The adult finless sole is 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 Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish swim. Apart from the tail or caudal fin, fish fins have no direct connection with the back bone and are supported only ...

is not attached to either the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

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. Along the

lateral line The lateral line, also called the lateral line organ (LLO), is a system of sensory organs found in fish, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelia ...

, there are normally two brown dots containing yellow flecks.

Distribution and habitat

This species occurs in the western Indian Ocean from the Red Sea to Sri Lanka and along the east coast of Africa to Durban. It is found in shallow, coastal waters where the seabed consists of sand or mud, often near coral reefs, and they feed mainly on

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". ...

invertebrates. It is caught for consumption, despite the poison it exudes and is marketed fresh. They often spend the day buried in the sand with only its eyes and nostrils visible.

Toxicity

The finless sole secretes a milky

ichthyotoxin Ichthyotoxins are compounds which are either toxic to fish, or are toxins produced by fish. The former include the algae-produced euglenophycin and prymnesins, which can cause large-scale fish deaths. The latter includes ostracitoxin, produced by b ...

from the base of its

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.

Eugenie Clark Eugenie Clark (May 4, 1922 – February 25, 2015), popularly known as The Shark Lady, was an American ichthyologist known for both her research on shark behavior and her study of fish in the order Tetraodontiformes. Clark was a pioneer in the fie ...

conducted much of the early work on the species. There is much biotechnological interest in pardaxin, early interest focused on potential

shark repellent A shark repellent is any method of driving sharks away from an area. Shark repellents are a category of animal repellents. Shark repellent technologies include magnetic shark repellent, electropositive shark repellents, electrical repellents, ...

applications while newer research focuses on antimicrobial and neurotoxic potential of pardaxin and its analogues. One toxin produced, pardaxin-1, does have unusual shark repellent and

surfactant Surfactants are chemical compounds that decrease the surface tension or interfacial tension between two liquids, a liquid and a gas, or a liquid and a solid. The word ''surfactant'' is a Blend word, blend of "surface-active agent", coined in ...

properties. It created voltage-dependent, ion-permeable channels in membranes and at high concentration it causes

lysis Lysis ( ; from Greek 'loosening') is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ...

in cell membranes. This toxin has been demonstrated to be 5–10 times more toxic,

cytolytic Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell. Water can enter the cell by diffusion through the cell membrane or through selective membrane channels ...

and active in the formation of pores in cell membranes than the other toxin exuded, pardaxin-2. Mimic Octopuses have been known to mimic them.

References

External links

* {{DEFAULTSORT:Pardachirus Marmoratus Soleidae Taxa named by Bernard Germain de Lacépède Fish described in 1802