Species Description: Echinolittorina ziczac is a small snail. Females reach a maximum length of 12 mm; males reach a length of about 6 mm (Abbot, 1954). They are roughly conical in shape with pronounced whorls and light vertical grooves. The aperture is small with a prominent lip. The base color of Echinolittorina ziczac is white, with dark brown or purplish zigzagging stripes; there is a salt-and-pepper effect to the pattern (Smith, 1951). The first few whorls, which make up the point of adult shells, are reddish brown with no striping. The inside of the shell is dark, purplish brown, and the operculum is dark brown (Abbot, 1954). Its body is a dark brown, small, rounded, with two small tentacles.
It resembles its close relatives, Echinolittorina angustior and Echinolittorina jamaicensis (frequently misidentified as Littorina lineolata) (Smith, 1951). It is also similar in appearance to Littorina angulifera, but can be distinguished from it by L. angulifera's larger size and paler operculum (Abbot, 1954).
Habitat & Regional Occurrence: Echinolittorina ziczac is present from Texas and south Florida to the Caribbean and Bermuda (Abbot, 1954). Locally they have been known to inhabit water as far north as the Sebastian Inlet but are not evenly distributed along the coast, being nearly absent at the St. Lucie Inlet despite its similar environment. This patchy distribution may be due to the vagaries of larval dispersal. (Janson, 1985). It can also be found in highly saline parts of the Loxahatchee River, in the vicinity of Jupiter Inlet (McPherson et al, 1984). E. ziczac prefers rocky areas where it hides in crevices in the rock. In areas without distinct zonation, it is a likely inhabitant of the higher intertidal, where the substratum is regularly wet but only submerged during the strongest tides (Stephenson and Stephenson, 1950). In places with distinct rocky intertidal zonation, it is usually found in the gray and black zones. E. ziczac can also be found on the upper and middle areas of sea walls (Stephenson and Stephenson, 1950). Their favored shores are sometimes associated with nearby stands or forests of mangroves (Abbot, 1954; Stephenson and Stephenson, 1950).
Physical Tolerances: E. ziczac appears to suffer mass mortalities related to cold temperatures (Borkowski, 1973). It also appears to have a poor tolerance for prolonged submersion and avoids being submerged for long periods of time (Stephenson and Stephenson, 1950).
Size, LifeSpan & Reproduction: E. ziczac is a sexually dimorphic species, with larger females than males. Also, males have more prominent grooves and more squat shells compared to females, whose shells are relatively smooth and tall (Abbot, 1954). Observations of populations near the Indian River Lagoon suggest they have an average lifespan of two years (Borkowski, 1973). Juveniles of E. ziczac and closely related species, about half a millimeter in length, settle out of the water column and begin life in the intertidal portion of the shore during the later half of the year (Borkowski, 1973). These juveniles grow quickly. Individuals settling in July or August commonly reach a size of 6 millimeters (the male adult size of E. ziczac) by the end of the growth period. Individuals not yet at their maximum size begin to grow rapidly again in February, growing fastest in May. (Borkowski, 1973; Abbot, 1954). During the summer, growth dramatically slows, ending by mid-September. Death occurs most frequently in the fall and winter, and as much as 80% of the population can die and be replaced by new recruits each year (Borkowski, 1973).
Echinolittorina ziczac reaches sexual maturity when near 6 mm. However, these and other Florida littorinids appear to put off their first spawning until their second year (Borkowski, 1973). Males transfer sperm directly to females during copulation, depositing the sperm in an organ called the bursa copulatrix. From there some of the sperm is transferred to the seminal receptacle, where the female stores it until ready to fertilize the eggs, while the rest is broken down and digested by the female (Borkowski, 1973). Spawn is generally released into the water during exceptionally strong high tides (Borkowski, 1973).
E. ziczac is sometimes a common and abundant inhabitant of the intertidal (Ekdale, 1974; Stephenson and Stephenson, 1950). It can also be relatively sparse, and make up very little of the intertidal biomass (Masi et al, 2009; Borkowski, 1973). However, even when it is not abundant, it can be a defining species of the gray zone in the intertidal (Masi et al, 2009; Stephenson and Stephenson, 1950).
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