Banded dune snail | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Mollusca |
Class: | Gastropoda |
Order: | Stylommatophora |
Family: | Xanthonychidae |
Genus: | Helminthoglypta |
Species: | H. walkeriana |
Binomial name | |
Helminthoglypta walkeriana (Hemphill, 1911) | |
Synonyms | |
Helix walkerianaHemphill, 1911 |
The banded dune snail or Morro shoulderband(Helminthoglypta walkeriana) is a species of endangered air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the subfamily Helminthoglyptinae. [3]
The name stems from the fact that the snails have distinctive spiral shells that are usually banded in different colors. The shells are typically mostly brown, however they can also be a variety of other colors.
At the time the species was divided into two subtaxa (subspecies or varieties): H. w. walkeriana and H. w. morroensis. The latter was thought to be extinct but was rediscovered. In 2004, it was elevated to species status as Helminthoglypta morroensis and it inherited the endangered status it had when it was part of Helminthoglypta walkeriana.
Both snails together were known as the banded dune snail. Today H. walkeriana proper is the Morro shoulderband, and H. morroensis is the Chorro shoulderband. [4]
The species is endemic to the area around the cities of Morro Bay and Los Osos in the central coast in San Luis Obispo County and Santa Barbara County, in California. As coastal organisms, the Morro Shoulderband variant primarily occupies coastal dunes, coastal dune scrubs, and maritime chaparral plant communities that are mostly stabilized dune systems. They are most commonly found on sandy soils dominated by woody shrubs. [5] On the other hand, the Chorro Shoulderband snail can also be found in grassland communities and rocky areas. It has also been found that there is a correlation between the Chorro Shoulderband’s occurrence and clay and serpentine soils. [6] Despite the slight variety in habitats, the total area of occurrence has been calculated to be as low as 40 km2 (15 sq mi). It is possible that only a few thousand individuals are living in the world now, mostly consisting of the Morro Shoulderband variety. However, the reproduction frequency of the snails allows them to maintain a population despite the variable conditions of the sandy habitats. The habitats are threatened not only by wind and water that can shift the sand dunes, but also by land conversion, off-road recreation, and the invasion of non-native plants. [7]
Although no study specific to the banded dune snails diet has been performed, it can be assumed that they have similar diets to those of the Helminthoglypta in similar locations, which consists of dead and decaying plant material. Similarly to other snails, the banded dune snail uses its sense of smell to find food. [4] Within the narrow distribution in coastal dune and scrub communities in western San Luis Obispo County, they typically expose themselves from underneath the sands during wet weather, meaning they are almost solely active during the wet seasons. They seal themselves inside of their shells for months during a drought, but reemerge when rains return. [8]
The rainy season is the morro shoulderband snail’s most active season. After spending many months in prolonged aestivation, they emerge following the first rain of the season. Their activity is reserved to either find food, which they do through their sense of smell, or to reproduce. High humidity correlates with higher levels of activity. Once the weather becomes drier, their activity decreases and they prepare for aestivation. During aestivation, they find shelter in local plants for as long as 170 days. This season can lead to a 40 percent loss in body weight, but this can be regained during the first 24 hours after aestivation. [8]
The life cycle of these snails is made up of two parts based on the dry and rainy weather of the Mediterranean climate regions of California. To survive drier seasons, they go through a period of prolonged dormancy, or aestivation. An epiphragm, a durable seal of dried mucus, is developed over the opening of its shell to protect itself from drying out. The epiphragm is then shed during the late fall and winter once rain begins. Most individual growth and reproduction occurs during the rainy season, when moisture conditions are ideal for feeding. They can mate several times in a single year. [8]
The reproductive cycle of the banded dune snail can be compared to other related Helminthoglypta species. Similarly to those species, the snails are hermaphroditic, meaning that all have both male and female reproductive organs. They are typically sexually mature at around 3–4 years of age. Prior to mating, which occurs after the first significant downpours of the wet season, they often engage in courtship behaviors to attract partners, which may include the exchange of pheromones. They generally mate when it is darker on the surface, meaning during overcast days or during the night. After mating, the female parts of the snail fertilize the eggs, then they are laid in shallow holes in sandy soil covered by leaves to protect them from predators or other environmental threats. The eggs, normally laid in small clusters, hatch around six months later. [8]
This snail was placed on the United States' Endangered Species List in 1994. the IUCN Red List considers the snail Critically Endangered, and NatureServe considers it Imperiled.
The USFWS recommends that the Morro shoulderband be downlisted to threatened status and the Chorro shoulderband be delisted. [4]
Aestivation is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. It takes place during times of heat and dryness, which are often the summer months.
Nicrophorus americanus, also known as the American burying beetle or giant carrion beetle, is a critically endangered species of beetle endemic to North America. It belongs to the order Coleoptera and the family Silphidae. The carrion beetle in North America is carnivorous, feeds on carrion and requires carrion to breed. It is also a member of one of the few genera of beetle to exhibit parental care. The decline of the American burying beetle has been attributed to habitat loss, alteration, and degradation, and they now occur in less than 10% of their historic range.
The Tehuantepec jackrabbit is a jackrabbit endemic to Mexico.
Dwarf forest, elfin forest, or pygmy forest is an uncommon ecosystem featuring miniature trees, inhabited by small species of fauna such as rodents and lizards. They are usually located at high elevations, under conditions of sufficient air humidity but poor soil. There are two main dwarf forest ecosystem types, involving different species and environmental characteristics: coastal temperate and montane tropical regions. Temperate coastal dwarf forest is common for parts of Southern California. Montane tropical forests are found across tropical highlands of Central America, northern South America and Southeast Asia. There are also other isolated examples of dwarf forests scattered across the world, while the largest dwarf forest is found in the Philippines.
The Anastasia Island beach mouse is a subspecies of the oldfield mouse of the southeastern United States. It occurs in the sand dunes of Florida beaches. It has been classified by the United States Fish and Wildlife Service as an endangered species due to the specificity of its habitat and the natural and human-induced destruction thereof.
Eriodictyon altissimum is a rare species of flowering plant in the borage family known by the common name Indian Knob mountainbalm. It is endemic to San Luis Obispo County, California, where it is known from only about six occurrences in the Irish Hills on the coast and nearby Indian Knob.
The flat-backed spider tortoise, more commonly known as the flat-tailed tortoise, and Madagascan flat-tailed tortoise, is a tortoise that belongs to the family Testudinidae. The various common names for this small tortoise usually refer to the noticeably flattened nature of its oblong upper-shell or its tail.
Achatinella livida is a critically endangered species of air-breathing land snail in the family Achatinellidae. This species is endemic to Oʻahu, Hawaiʻi.
Helminthoglypta is a genus of air-breathing land snails, terrestrial pulmonate gastropod mollusks in the subfamily Helminthoglyptinae of the family Xanthonychidae.
The Chittenango ovate amber snail is a species of small air-breathing land snail in the family Succineidae, the amber snails. This species was discovered in 1905, and was reported three years later as a subspecies of the oval ambersnail, Succinea ovalis. Several taxonomic reviews took place in the subsequent decades until the end of the 1980s, when the Chittenango ovate amber snail was finally judged to be a distinct species based on chemical and morphological data.
The Guyandotte River crayfish is a species of crayfish found in a small stream system in Wyoming County, West Virginia, US. They are closely related to the Big Sandy crayfish, and until recently, the two were thought to belong to the same species. The Guyandotte River crayfish is currently listed as Data Deficient by the IUCN and was listed under the Endangered Species Act with the Big Sandy crayfish on April 4, 2016.
Melicope paniculata, the Lihue melicope, is a rare species of tree in the family Rutaceae. It is endemic to the Hawaiian Islands. Like other Hawaiian Melicope, this species is known as alani.
Arctostaphylos morroensis is a species of manzanita known by the common name Morro manzanita. This shrub is endemic to San Luis Obispo County, California, where it is known only from the vicinity of Morro Bay.
Theba pisana, common names the white garden snail, sand hill snail, white Italian snail, Mediterranean coastal snail, and simply just the Mediterranean snail, is an edible species of medium-sized, air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Helicidae, the typical snails.
Orthalicus reses, the Stock Island tree snail or the Florida tree snail, is a species of large tropical air-breathing tree snail, a terrestrial pulmonate gastropod mollusk in the family Orthalicidae. It was first described in 1830 by the American naturalist Thomas Say. The holotype, a specimen probably collected in Key West, was subsequently lost. Over a hundred years later, in 1946, the American biologist Henry Augustus Pilsbry redescribed the species using a specimen from Stock Island, Florida. Orthalicus reses has two subspecies, O. reses reses and O. reses nosodryas. The validity of these two taxa is still being discussed, but some experts argue that considering them as independent units may be important for management purposes.
The Guadalupe-Nipomo Dunes National Wildlife Refuge is a 2,553-acre (10.33 km2) protected area located along the Central Coast of California, in southern San Luis Obispo and northern Santa Barbara Counties.
Suaeda californica is a rare species of flowering plant in the amaranth family known by the common name California seablite. It is now endemic to San Luis Obispo County, California, where it is known from a few occurrences in the marshes around Morro Bay, historical populations around San Francisco Bay have been extirpated.
Myotis septentrionalis, known as the northern long-eared bat or northern myotis, is a species of bat native to North America. There are no recognized subspecies. The northern long-eared bat is about 3–3.7 inches in length, with a wingspan of 9–10 inches. It is distinguishable by its long ears when comparing it to other bats in its genus. This species is commonly found in the northern United States and Southern Canada east of British Columbia. The geographic range includes 37 states.
Habroscelimorpha dorsalis dorsalis, commonly known as the northeastern beach tiger beetle, is the largest subspecies of eastern beach tiger beetle. In 2012, Cicindela dorsalis dorsalis was reclassified under the name Habroscelimorpha dorsalis dorsalis, but the names are used synonymously in recently published literature. Fitting to its common name, the northeastern beach tiger beetle dwells along the U.S. northeast coast in small sand burrows. The beetle is diurnal and can be spotted by its light tan coloring with dark lines and green hues on its thorax and head.
Helminthoglypta arrosa, also known as the bronze shoulderband snail, is a North American species of air-breathing land snail. It is found in northern and central California, and is endemic to the state.