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| The Eelgrass Limpet (extinct) was a marine invertebrate last recorded in 1929. It was a gastropod, which means that it moved by means of a large foot. It possessed a single pair of reduced marginal teeth on the radula, which is a file-like structure used for scraping off and drawing food into the mouth. Biology : The Eelgrass Limpet fed on epithelial (tissue-forming outer layers) cells of eelgrass rather than on epiphytic diatoms and algae. Its habits were more specialized, and its ranges and tolerances more narrow, than most marine invertebrates. Habitat : The Northwest Atlantic subspecies of the Eelgrass Limpet occurred solely on the blades of the North Atlantic Eelgrass, Zostera marina. Individual limpets probably became detached from the eelgrass by wave action. Sometimes they were found on other substrates, such as the periwinkle Littorina littoria. All locations in which the species was collected appeared to be fully marine rather than estuarine habitats. Other molluscs that were collected near the species included strictly marine species, as well. No collections indicate that the species lived in low salinity (brackish water) sites. Thus, the Eelgrass Limpet was probably a stenohaline species of open coastal waters. |
| The Dwarf Wedgemussel (extirpated) a freshwater mussel is small (< 55 mm long) and roughly trapezoidal in shape. The outside of the shell is brown or yellowish-brown, with greenish rays visible in young or pale-coloured specimens. The nacre is bluish or silvery white and is iridescent in the posterior part of the shell. The hinge teeth are small but distinct. This species is unique in that it has two lateral teeth in the right valve and one in the left; other species have two lateral teeth in the left valve and one in the right. Habitat : The mussel is found in small streams to medium-sized rivers with slow to moderate current and fine sediment, sand or gravel substrates. It appears to have poor tolerance for suspended silt. Stream-side vegetation seems to be required. Biology : The parasitic larvae (glochidia) are released in the spring. The host fish species for the glochidia in the wild are not known, but five species of fish are able to serve as hosts in the laboratory. Of these, only Atlantic Salmon (Salmo salar) occurred in the Petitcodiac watershed. The maximum life span of the mussel is believed to be 12-18 years. |
| The Puget Oregonian Snail (extirpated) is a member of the Polygrid family, a large and diverse group of land snails that are found only in North America. The spiral shells of mature individuals are pale yellowish to brown, with a slightly flattened, globe-like shape, and five to six whorls that increase regularly in diameter. The aperture (opening in the shell) has a broad, whitish lip that is obviously bent backwards. There is also a tooth-like structure on the inside of the second-last whorl of the shell that sticks out into the aperture. The shells of adults are 18 to 26 mm in diameter. The body of the snail is light brown, and may have a lilac undertone. Young snails superficially resemble the adults, but lack both the lip at the aperture and the tooth-like structure. Habitat : No information is available on the habitats previously used by the Puget Oregonian Snail in Canada. In the United States, the snail lives in moist, old-growth forests, and forested riverbank areas at low and middle elevations. Essential habitat characteristics include: shade provided by the forest canopy, which conserves moisture and buffers fluctuations in temperature and moisture conditions on the forest floor; coarse woody debris and leaf litter for escape cover and egg-laying sites; and fungi for food. Biology : Little is known of the ecology and life history of the Puget Oregonian Snail. The snails are hermaphroditic (have both male and female sexual organs) and move by creeping along on a sucker-like foot. Like other forest-dwelling land snails, the Puget Oregonian Snail probably needs protected, moist locations to lay eggs, takes at least five years to become sexually mature, and is long-lived. The diet of the Puget Oregonian Snail is unknown, but it is suspected to include plants and fungi. A wide variety of mammals, birds, amphibians, reptiles, and other invertebrates feed on land snails. The scattered distribution of the species throughout its range has led to the conclusion that the Puget Oregonian Snail is not very adept at dispersing to new locations. The poor ability of the snail to disperse probably means that, if it disappears from a local habitat patch, it is unlikely to repopulate that spot through immigration from another population. |
| The Banff Springs Snail (endangered) is small and globe-shaped with heavy, uneven growth lines. It is short, dark-reddish, and sometimes has a faintly striped spire. It measures 5.5 to 7.5 mm in length and is 4 to 5.5 mm wide. Like other members of the Physidae family, it is sinistrally coiled (meaning the aperture is on the left when the spire is pointing up). The aperture on other North American freshwater snails is on the right. Habitat : The species appears to have an extremely restricted micro-distribution. For example, more than 90 % of the Cave Spring population is found in or near the spring's origin. However, 36 to 93 % of the Basin Spring population is found in the pool. Hot thermal springs are harsh environments, given their high temperatures and low levels of dissolved oxygen. The snails seem to prefer water between 30� and 36�C. Biology : The snail is believed to be capable of self or cross-fertilization. Since very small snails were seen throughout the year in 1996, it is thought that reproduction may occur year round. The snail likely grazes on plant matter and microbes (algae/bacteria). |
| The Hotwater Physa (endangered) is a freshwater gastropod with a high spired and sinistrally coiled shell. Members of Physella have digitations on the parietal side of the mantle only. The shell of this mollusc is very small, narrowly elongate-ovate and ranges in size from 3.25 to 9.1 mm. The aperture is ear-shaped and its rim has an outer lip callus and a curved perimeter. Habitat :Where Hotwater Physas are found, Alpha Stream is about 2 m wide. Water temperatures varied from 23.5 to 36�C on October 1, 1997, when the air temperature was 0�C. At the head of the stream on the same date the water temperature was 36.5�C, the pH was 7.8, and the water was saturated with 67% dissolved oxygen. The water from the pool enters Alpha Stream through a dam at a rate of 80-81 liters/second. Biology :Members of the family Physidae are detritivores and/or bacterial feeders. In Alpha Stream, Hotwater Physas are found mostly among mats of Chara, but also in dense assemblages on the soft sediments. Snails were also observed grazing on paper birch leaves that had fallen into the stream. Hotwater Physas kept in the lab grazed on a sprinkled mixture of two-thirds brewers� yeast and one-third fish flake food. Physids are oviparous hermaphrodites. Most breed only once. The adults reproduce in the spring and die after the eggs are laid. Thus there is a complete replacement of generations annually. In the lab, clear crescent-shaped gelatinous egg masses containing 6 to 18 eggs were laid above the water line where the temperature was about 25�C. Hatching occurred after about nine days. |
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