Mucus, from the epidermis of the sole, and urea, from the urine of a nearby host, can stimulate eggs to hatch, possibly increasing the chances of larvae to make contact with a host. During the oncomiracidium stage, individuals of Entobdella soleae find their hosts by chemoreception to a substance secreted by the host's mucus cells in its epidermis. A theorized search pattern for hosts is accomplished with the coupling of horizontal transport of larvae by water currents and photopositive and photonegative vertical movements. Photopositive vertical movements become less frequent as the larvae grow older. Larvae have also been shown to find prey in the presence of only infra-red light. It is hypothesized that pheromone attractions allow for early mating among the individuals.
Other Communication Modes: pheromones
Perception Channels: infrared/heat ; chemical
Entobdella soleae has no special conservation status.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
The life cycle of Entobdella soleae is largely dependent on the presence and hypoactivity of a host sole. Individuals secured to the lower surface of the host lay eggs that become secured to the substrate via a sticky coating. This prevents the eggs from being taken away from a population of hosts by currents should the parental host change location. After approximately a month of development, larvae emerge from the egg within 5 minutes of being activated by an environmental stimulus. Studies suggest that the hatching of the eggs is rhythmic with respect to light and that sole mucous or urea activate the embryos. The larval form that hatches from the egg is referred to as an oncomiracidium. This free swimming larvae locates a host; attachment may occur as quickly as 2 minutes after hatching and must be completed within 24 hours, before the oncomiracidium depletes its energy and dies. The oncomiracidium attaches to the host’s upper anterior surface before migrating to the lower surface. Upon attachment, the parasite sheds its ciliated epidermal cells. The exact duration of the larval stage is not reported in literature. However, it is suggested to last approximately 40 days, the length of time required to complete the migration process to the lower surface of the host where it subsequently reaches sexual maturity. Thus, with the exception of the egg, there is little to no uninfective period throughout the life cycle of E. soleae.
Development - Life Cycle: metamorphosis
Because Entobdella soleae is a skin parasite capable of causing death of its host, Solea solea, this monogenean parasite is an economic hindrance for humans. Solea solea is a versatile fish used in cooking and highly valued for its taste in Europe.
There are no known positive effects of Entobdella soleae on humans.
Entobdella soleae is a skin parasite. The host is specific for this monogenean parasite and is Solea solea, a flatfish. In the wild, only a few parasites are found on a given host. In fish farms, a few hundred parasites can be found per fish, causing mass skin inflammation and death.
Ecosystem Impact: parasite
Species Used as Host:
Entobdella soleae is a skin parasite of Solea solea and uses its pharynx as its feeding organ. There are glands in the pharynx that secrete proteolytic enzymes to digest the epidermis of the flatfish. The pharynx sucks in the digested food in liquid form for absorption in the intestinal diverticula.
Animal Foods: fish
Primary Diet: carnivore (Piscivore )
Entobdella soleae is a monogenean flatworm and an ectoparasite of the common sole (Solae solae). As such, its range is limited to geographic areas inhabited by the common sole, mostly in the eastern Atlantic Ocean from Norway to Senegal and in the Mediterranean Sea. The common sole is frequently harvested for food in Europe, and a large number of parasitic infections by E. soleae have been reported in captivity.
Biogeographic Regions: atlantic ocean (Native ); mediterranean sea (Native )
Entobdella soleae is generally found in temperate, marine environments high in host availability. Entobdella soleae has extremely high host exclusivity, with literature citing only three possible host species, all within genus Solae, with a strong preference for Solae solae over other soleid fish. Solae solae is most commonly found hidden within the sand or mud in shallow waters. While larvae may initially be free-swimming, adults live exclusively on the skin of the host. A free-swimming larva will attach to the dorsum of the host and migrate toward the host's ventral surface, which is in contact with the sea floor, where it completes development and reproduces.
Range depth: 0 to 152 m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: benthic
Individuals of Entobdella soleae have a lifespan of up to 6.5 months. There is no observed difference between those individuals obtained from the wild and those grown in a laboratory setting.
Range lifespan
Status: wild: 6.5 (high) months.
Range lifespan
Status: captivity: 6.5 (high) months.
The average size of Entobdella soleae has not been clearly defined in the current literature. However, studies reference specimens of 2 to 6 mm in length. Entobdella soleae exhibits the typical monogenean body plan. It is flat, translucent, and has a large, disc-shaped haptor, a posterior organ used for semi-permanent attachment to the host. A distinguishing feature of the organism is its unique prohaptor, an anterior structure with two adhesive pads. These adhesive pads secrete a strong cement that temporarily attaches the organism to a substrate and are critical for locomotion.
Range length: 2 to 6 mm.
Other Physical Features: ectothermic ; bilateral symmetry
There are no known predators of Entobdella soleae reported in literature.
Due to the relatively low population density of Entobdella soleae in the wild, (1 to 3 individuals per host), it has been suggested that there is a mechanism for pheromonal attraction between individuals. This is supported by the fact that there is a layer of stagnant water between the host sole and the sea floor. This small but stable volume of water would allow for pheromones to be transmitted without interruption from current and may be part of the reason that adults migrate to the lower surface of the host. Due to the lack of concrete evidence, however, the exact mechanism for the attraction of mates has yet to be determined.
Entobdella soleae is a protandrous hermaphrodite that reproduces sexually. Although each organism houses both male and female organs, it is believed that self-fertilization is not possible due to the fact that the male reproductive organs cease to operate at the same time the female reproductive organs become active. Clutch size and gestation period of this hermaphroditic monogenean are highly variable depending on the size of the individual. One study found that medium to large individuals may produce 30 to 60 eggs a day with gestation periods lasting anywhere from 5 seconds to 168 minutes. Additionally, as the size of the organism increases, there is a slight increase in the size of the eggs produced.
Range gestation period: 0.08 to 168 minutes.
Key Reproductive Features: iteroparous ; sequential hermaphrodite (Protandrous ); sexual ; oviparous
Entobdella soleae does not provide any parental involvement.
Parental Investment: no parental involvement
