Entobdella soleae
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| Entobdella soleae | |
|---|---|
Scientific classification  | |
| Missing taxonomy template (fix): | Entobdella |
| Species: | Template:Taxonomy/EntobdellaE. soleae |
| Binomial name | |
| Template:Taxonomy/EntobdellaEntobdella soleae van Beneden & Hesse, 1864 | |
Entobdella soleae is a monogenean (Platyhelminth) skin parasite of the common sole, Solea solea, an important food fish. They are approximately 2 to 6 mm in length. It is flat, translucent, and has a large, disc-shaped haptor, a posterior organ used for semi-permanent attachment to the host.[1] Typically, 2-6 parasites are found on wild sole, but in intensive fish farms this can rise to 200-300 parasites per fish, causing skin inflammation and sometimes death of the sole. E. soleae can live up to 120 days in seawater.[2]
The life cycle of Entobdella soleae follows the life patterns of their marine bottom-living host. The Solea solea would bury itself in the sediment for some time each day. The parasites are attached to the bottom of their host, in which when their hosts bury themselves, the parasite lays their eggs. The eggs are anchored to the sea bottom so that they wouldn't be swept away by the water currents. When the eggs hatched the oncomiracidia emerges and invades the anterior part of the upper surface of the fish. This part of the fish is the only part that is exposed when the fish is buried. After entering and developing on the upper surface of the fish, it migrates down toward the lower surface of the fish where they reach sexual maturity. Adult parasite would distribute throughout the lower surface of the host and are oriented with the adhesive organ upstream.[3]
Larvae
Entobdella soleae larvae are called oncomiracidia. They are free-swimming and ciliated. These oncomiracidia are likely to attach to the host's upper surface where they migrate forwards toward the fish's head and then migrate to the underside of the sole, where they remain.[4]
Attachment and detachment
Entobdella soleae utilizes suction through a posterior disc-shaped haptor to achieve semi-permanent attachment to the sole's skin.[5] E. soleae demonstrate host-specific behavior by attaching to the sole epidermis by the presence of sole mucous cells.[6]
The characteristic of the pad tegument might demonstrate a possible role in detachment of the parasite to the host. These features include an isolated tegument and the microvillus surface network of the pad tegument.[5]
Adhesive pad
The surface of the adhesive pads of E. soleae is encompassed by tegument that contains perforations of numerous rod-carrying ducts through pepper-pot apertures and ducts of spheroidal secretory bodies. Rods are distributed uniformly and intensely electron-dense within their ducts. Spheroidal secretory bodies are both tightly packed and have less electron density than rods. Moreover, the tegument on the surface of the parasite is isolated from the general tegumentary syncytium by a cell boundary. The tegument also contains secretory bodies.[5]
A 4-5 μm layer of cement bonds the adhesive pad of E. soleae via tegumental microvilli and the sole's epidermal furrows during attachment. Rod-shaped secretory bodies are the major substance of the cement.[5]