Overview

Brief Summary

Spondylus americanus is a sessile bivalve, occurring in shallow water in the Atlantic Ocean from Brazil to North Carolina, where it is usually found as part of a coral reef. Like all Spondylidae, Spondylus americanus is noted for its striking, spiny appearance, giving rise to its common name, the Atlantic Thorny Oyster.

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Distribution

Spondylus americanus is primarily found in the western-hemisphere, ranging along the Atlantic coastline from Brazil and Caribbean states such as Trinidad & Tobago (10° 40′ 0″ N, 61° 31′ 0″ W), to as far north as the Gulf of Mexico, Bermuda (32° 18′ 0″ N, 64° 47′ 0″ W) and the coast of North Carolina (33° 50 0″ N to 36° 35 0″ N 75° 28 0″W) (Tunnell et al., 2010: 330; Wells, 1988: 301; Logan, 1974: 574).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Physical Description

Morphology

Shell: The outer shell layer is thick, composed of calcite (Logan, 1974: 571), and ranges from red-orange to yellow in color, with a circular shape and no apparent periostracum (Tunnell et al., 2010: 330). The striations on the shell are pronounced, and the outer layer is interspersed randomly with large spines. Below lie several aragonite layers, and the internal surface is concave as well as smooth and white, although ring-like structures may also be seen (Yonge, 1973: 176; Logan, 1974: 571-572; Tunnell et al., 2010: 330).

The valve which houses the internal organs is the larger of the two, and projects dorsally from the hinge (Yonge, 1973: 176; Dakin, 1928a: 338). The lower valve is typically flat on the superficial level connected to a surface, as opposed to the rounded shape of the upper valve (Dakin, 1928a: 338).

An interlocking pair of hinge teeth and sockets connects the valves, along with a large ligament in the center of the hinge plate (Tunnell et al., 2010: 330; Yonge, 1973: 177). This pair of teeth is unique to Spondylidae (Yonge, 1973: 184).

Mantle: The middle of three mantle folds houses a row of short tentacles and eyes, while the innermost fold is muscular and dappled with brown (Logan, 1974: 570; Yonge, 1973: 177). The eyes on Spondylus americana are of a relatively small size, and there are 92 on the upper valve and 71 on the lower valve (Dakin, 1928b: 356).

Internal organs: There is a single, central adductor muscle responsible for closing the shell; the muscle is particularly well-developed in this species to facilitate this task (Yonge, 1973: 177; Dakin, 1928a: 342). The ctenidia are attached only to a suspending membrane (Yonge, 1973: 177). The series of filaments that compose the ctenidia are attached to one another via ciliated disks (Yonge, 1973: 177). Some of the filaments also have an enlarged region of blood vessels (Dakin, 1928a: 344).

The labial palps are relatively large, and the lips may stretch an average of 2 cm, with the ends being an orange-yellow color (Yonge, 1973: 178-179; Dakin, 1928a: 344). The nervous system is centered around a developed ganglion on the adductor muscle (Dakin, 1928a: 345).

Foot: The foot serves the function of cleaning the interior of the shell, as cementation frees it from having to anchor Spondylus americanus to the substrate (Yonge, 1973: 180-181). Cilia are present to aid in transporting particles; when large groups of particles are built up, they can then be expelled (Yonge, 1973: 181).

Size: 74mm to 230mm along the anteroposterior axis (Tunnell et al., 2010: 330).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Diagnostic Description

Spondylus americanus ranges from 76mm to 230mm in size along the anteroposterior axis (Tunnell et al., 2010: 330), and is distinguished by a typical red-orange to yellow coloration (Logan, 1974: 570-571). The spines on the outer shell common to members of the family Spondylidae are typically of 50mm or less in length in this species, longer than those of most other spondylids (Weisbord, 1964: 166). Although other members of the family Spondylidae are typically a solid, dark color, Spondylus americanus may sometimes appear as a flat white with small spots of purple, red and orange, making it easier to identify (Lamprell, 1987: 54).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Look Alikes

Generally, members of the family Spondylidae will look similar to each other because of the presence of spines; Spondylus princeps appears most alike, although its red coloration and shorter spines distinguish it from the more muted yellow shell of Spondylus americanus (Weisbord, 1964: 166).

A resemblance between Spondylus americanus and members of the family Pectinidae has been noted, especially with respect to the eyes arrayed on the mantle of Spondylus americanus and any Pectinidae, and a brief study of the internal organs will reveal little difference between the two (Dakin, 1928a: 338; Yonge, 1973: 177). However, Spondylus americanus is easily distinguished from any Pectinidae by its long spines and overlapping valves (Dakin, 1928a: 338).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Ecology

Habitat

Known from seamounts and knolls
  • Stocks, K. 2009. Seamounts Online: an online information system for seamount biology. Version 2009-1. World Wide Web electronic publication.
translation missing: en.license_cc_by_4_0

© WoRMS for SMEBD

Source: World Register of Marine Species

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Depth range based on 27 specimens in 1 taxon.
Water temperature and chemistry ranges based on 9 samples.

Environmental ranges
  Depth range (m): 1.4 - 96
  Temperature range (°C): 22.429 - 25.691
  Nitrate (umol/L): 0.757 - 2.285
  Salinity (PPS): 36.186 - 36.901
  Oxygen (ml/l): 4.519 - 4.895
  Phosphate (umol/l): 0.093 - 0.222
  Silicate (umol/l): 0.993 - 2.616

Graphical representation

Depth range (m): 1.4 - 96

Temperature range (°C): 22.429 - 25.691

Nitrate (umol/L): 0.757 - 2.285

Salinity (PPS): 36.186 - 36.901

Oxygen (ml/l): 4.519 - 4.895

Phosphate (umol/l): 0.093 - 0.222

Silicate (umol/l): 0.993 - 2.616
 
Note: this information has not been validated. Check this *note*. Your feedback is most welcome.

Trusted

Article rating from 0 people

Default rating: 2.5 of 5

Spondylus americanus typically inhabits shallow water bodies that may be enclosed, such as lagoons, or unenclosed, at depths of 10m to 168m (Tunnell et al., 2010: 330; Logan, 1974: 576). As part of the epifaunal community of its habitats, the adolescent Spondylus americanus will traverse surfaces until it finds a suitable settling spot, where the adult will typically remain (Logan, 1974: 573).

Calcium carbonate is necessary for spine development and cementation to a substrate, and Spondylus americanus will attempt to dwell on or around coral in order to easily fulfill the requirements for that substance (Logan, 1974: 569). A variety of substrate shapes are suitable: the species’ shell will adapt to even narrow clefts (Logan, 1974: 573). The presence of coral is desirable, but by no means necessary for life once matured, as sand-dwelling, non-cemented adults have also been found (Logan, 1974: 576, 578). However, life on the substrate is more sustainable, as Spondylus americanus is protected from the turbulence of storms (Logan, 1974: 578).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Dispersal

The larval stage of Spondylus americanus has not been observed, but presumably the larvae are free-swimming until choosing a substrate to attach to and develop into the postlarval stage (Logan, 1974: 573). Adults will remain attached to the substrate unless they have been forcibly detached (Logan, 1974: 578).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Trophic Strategy

Spondylus americanus is a heterotrophic organism, relying on omnivorous filter feeding to attain sustenance (Logan, 1974: 569). Water is brought in past the marginal denticles at the edge of the shell where particles may be foraged from the water to serve as nutrients (Logan, 1974: 579).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

General Ecology

Spondylus americanus is found in mostly tropical regions in the Atlantic, where there is an abundance of calcium carbonate from coral reefs in the area. The calcium carbonate molecule is instrumental in the development of the species' spines and cementation, so Spondylus americanus will seek to settle near coral formations (Logan, 1974: 569). They can then become members of the coral ecosystem, serving as roosts for epibiontic algae which camouflage the shell, as well as being subject to predators such as gastropods, and lobsters (Logan, 1974: 581; Feifarek, 1987).

A few other organisms prey on Spondylus americanus, including octopi and fish such as wrasses, although specific species that act as predators towards the species have not been recorded (Logan, 1974: 583-584). It is likely that the sharp spines defend against predators, and successful cementation to a substrate has been shown to increase survivability against predators (Logan, 1974: 583; Harper, 1990: 457). Although Parrot fish are not natural predators of the species, as they consume the algae lining the shell as camouflage, they may decrease Spondylus americanus’s survivability (Logan, 1974: 583).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Life History and Behavior

Behavior

The larvae are most likely motile, seeking suitable substrates to settle on (Logan, 1974: 573). Adult Spondylus americanus live a sessile existence, relying on filter feeding for sustenance and defense via sealing the valves (Logan, 1974: 569). If necessary, flapping of the valves allows the organism to swim, and may be useful in spreading sexual products during reproduction and possibly evading predators if S. americanus becomes detached from the substrate (Dakin, 1928a: 342; Drew, 1906: 34).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Life Cycle

No documentation of the eggs and pre-juvenile stages of Spondylus americanus exists, but that data is available for members of the family Pectinidae, with which Spondylus americanus shares some similarities; possibly the larval stages are alike (Logan, 1974: 573). Pecten irradians hatches from the egg as a free-swimming, ciliated trocophore, before developing into a veliger which may feed using the velum (Fay et al., 1983: 4). The foot is the final development of this stage (Fay et al., 1983: 5).

The juvenile stage of S. americanus, following the veliger, finds a surface to attach to with the byssus (Logan, 1974: 573). Following metamorphosis into the postlarval stage, the byssus attaches to the chosen substrate, to be followed soon by cementation, when the byssal notch is filled (Yonge, 1973: 176; Logan, 1974: 573).

Eventual size of the shell and spines depends on the area the larva chooses to attach to: the valves have some plasticity to adapt for proper function in narrow places. Spines grow at random angles before resolving to the large spines pointed away from the shell seen in adult Spondylus americanus; older spines are usually ground away by this point (Logan, 1974: 573-574).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Life Expectancy

The life expectancy of Spondylus americanus has not been recorded as of March, 2011.

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Reproduction

The sexual organs of Spondylus americanus, which has separate sexes, are located beneath the foot within the visceral mass (Logan, 1974: 572; Dakin, 1928a: 354). Reproductive morphology is very similar to that of members of the family Pectinidae (Dakin, 1928a: 353); a look at the sexual organs of Pecten tenuicostatus may suffice as they have not been sufficiently documented for Spondylus americanus. The reproductive organs of this species will swell when sexual activity is imminent (Dakin, 1928a: 354). Ducts from the organs connect to the kidneys, which then work to disperse eggs or sperm into the water-this may be accompanied by a flapping of the shell to further spread out the sperm and eggs. During this process, Pecten tenuicostatus appears docile and sedentary, reacting little to the surroundings (Drew: 1906, 34). Spawning in Spondylidae will occur in warm water during the summer, sometimes as late as August (Logan, 1974: 572).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Evolution and Systematics

Evolution

The fossil record of Spondylidae extends to the early Jurassic, although spinous bivalves that existed during the late Paleozoic may be ancestors (Logan, 1974: 584). Spondylus americanus' particular evolution does not appear to have been studied, but with respect to the family as a whole, one of these potential ancestors may be the Pectinidae of the Carboniferous (Dakin, 1928a: 354).

The Pectinidae have unique eyes among the bivalves that are homologous to those found in Spondylus americanus (Dakin, 1928b: 356). both families rest on the same valve (Dakin, 1928a: 337, 338). The mantle, adductor muscle, and radial muscle characteristics that have been specialized in Pectinidae are mostly shared in Spondylidae as well (Dakin, 1928a: 338-342). The ctenidia of both families have a “Respiratory Expansion” that also appears unique (Dakin, 1928a: 344).

The features of pectinids were adapted for swimming, but as a sessile species, Spondylus americanus has experienced changes in the function of some organs: while the adductor muscle is similar, Spondylus americanus’ has more development in the area designed to close the shell (Dakin, 1928a: 342).

Dakin (1928a) implied that the sister-group of Spondylidae may be Pecten maximus. Retractor muscles controlling the foot are reduced in the Pectinidae, and even vestigial in Pecten maximus; in Spondylidae, they are absent (Dakin, 1928a: 343). The particular organization of the intestine among the other organs unique to Pecten maximus among the other Pectinidae is the same organization found in the Spondylidae (Dakin, 1928a: 345). The unique nervous system of the Spondylidae appears derived from that of Pectinidae, with developed visceral ganglia, and again is most similar to Pecten maximus (Dakin, 1928a: 349, 352).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Physiology and Cell Biology

Cell Biology

No cytology data currently available (as of March, 2011).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology and Genetics

Genetics

No genetic data is currently available for Spondylus americanus (as of March 2011).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Molecular Biology

No molecular data currently available (as of March 2011).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Conservation

Conservation Status

Spondylus americanus is threatened by predators, but not to the extent that conservational efforts will be required (Logan, 1974: 583-584; Feifarek, 1987). Human factors such as pollution or overfishing are probably not major threats to Spondylus americanus either (Mikkelsen, 2003: 454).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Relevance to Humans and Ecosystems

Benefits

Spondylidae are generally edible, and may be consumed where they are commonly found. The shell is something of a collector's item because of the large adorning spines.

Research focusing on Spondylus varius reveals it to have hepatoprotective properties, preventing the human liver from damage; whether the same holds for Spondylus americanus remains to be seen (Koyama et al., 2006: 729-731). Because it is a filter feeder, Spondylus americanus can also be of benefit to the oceanic ecosystems it is a part of, redistributing nutrients and clearing out particles suspended in water (Peterson and Lubchenco, 1997: 182).

Public Domain

Field Museum of Natural History

Source: Field Museum phylogenetics class

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Wikipedia

Spondylus americanus

Spondylus americanus, the Atlantic thorny oyster, is a species of bivalve mollusc in the family Limidae. It can be found along the Atlantic coast of North America, ranging from North Carolina to Brazil.[2]

Description[edit]

The Atlantic thorny oyster can grow to 10 centimetres (3.9 in) in diameter. The valves of the shell are roughly circular and the upper one is decorated with many spiny protuberances up to 5 centimetres (2.0 in) long. When growing in a crevice, the shape of the shell adapts itself to the available space.[3] The colour varies but is usually white or cream with orange or purplish areas making it well camouflaged. The lower valve is flat and is attached to the substrate. When the living animal is lying on the seabed it is usually not visible because of the algae, marine animals and sediment that cover the shell. The flat tree oyster and Lister's tree oyster are often among these epibionts.[4] A diver swimming past may just observe a slight movement on the seabed as the oyster snaps its valves shut. Young animals are much less spiny than adults and resemble members of the genus Chama, the jewelbox clams.[5][6]

Distribution and habitat[edit]

The Atlantic thorny oyster occurs in the western Atlantic Ocean, the Caribbean Sea and Gulf of Mexico where it is found at depths between 9 and 45 metres (30 and 148 ft). Its range extends from North Carolina and Texas southwards to Venezuela and Brazil. It occurs on deep water reefs especially in areas with high sedimentation. It is often lodged in a crevice or concealed under an overhang. It is also a member of the fouling community, being found on sea walls, man made structures and wrecks.[5][6]

Biology[edit]

The Atlantic thorny oyster is a filter feeder sifting out plankton and other organic material from the water that passes over its gills. Little is known of its breeding habits but the larvae are planktonic, seeking out suitable locations on which to settle. Areas with suitable calcareous matter for building the shell are favoured. The adults are sedentary and normally occupy the same position for the rest of their lives unless shifted by storms.[3]

References[edit]

  1. ^ a b Huber, Markus (2010). "Spondylus americanus Hermann, 1781". World Register of Marine Species. Retrieved 2012-10-03. 
  2. ^ Abbott, R.T. & Morris, P.A. A Field Guide to Shells: Atlantic and Gulf Coasts and the West Indies. New York: Houghton Mifflin, 1995. 33.
  3. ^ a b "Spondylus americanus". Encyclopedia of Life. Retrieved 2012-10-04. 
  4. ^ Colin, Patrick L. (1978). Marine Invertebrates and Plants of the Living Reef. T.F.H. Publications. p. 390. ISBN 0-86622-875-6. 
  5. ^ a b Colin, Patrick L. (1978). Marine Invertebrates and Plants of the Living Reef. T.F.H. Publications. pp. 390–391. ISBN 0-86622-875-6. 
  6. ^ a b "Atlantic thorny-oyster (Spondylus americanus)". Interactive Guide to Caribbean Diving. Marine Species Identification Portal. Retrieved 2012-10-04. 
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia

Unreviewed

Article rating from 0 people

Default rating: 2.5 of 5

Disclaimer

EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.

To request an improvement, please leave a comment on the page. Thank you!