Common names: Brittlestar
Synonyms: Amphiura pulchella Lyman, 1869
Species Description: Fine scales cover the disk of Amphiodia pulchella, and the pairs of radial shields on the dorsal surface of the disk are closely joined (Hendler et al. 1995). Primary plates are prominent on the disks of smaller specimens, but are usually absent on larger individuals. The middle arm spine is dorsoventrally flattened, with a truncate, echinulate tip. The tips of the other two spines are bluntly rounded. Both distal pairs of oral papillae are elongate with blunt tips, and each of the tube feet have a bulbous tip.
The color of the disk can vary from gray to brownish gray, with reddish or purplish gray marking the primary plates and other large scales. The radial shields are dark near the center of the disk with a pale distal tip. Reddish brown pigmentation of the stomach may be visible through the body wall. The color of the arms is variable, often pale gray, blotched or having dark gray, brown or reddish brown bands. A dusky internal spot is usually visible on the arm spines, and a light mid-dorsal arm stripe is sometimes evident (Thomas 1962), which is likely from the visibility of the vertebrae through the thin dorsal arm plates (Hendler et al. 1995).
Potentially Misidentified Species: In some parts of its range, A. pulchella may be confused with the similar but slightly larger A. atra. However, A. atra is reportedly absent in southern Florida and the Florida Keys (Hendler et al. 1995). Furthermore, A. pulchella is easily distinguished from A. atra and other shallow-water Amphiodia and Amphipholis species by the presence of only a single tentacle scale.
Habitat & Regional Occurrence: A. pulchella occupies shallow burrows in soft sediments at depths from 1 to 71 m, often in back reef areas along with seagrasses and sponges, or among coral colonies and clumps of algae such as Halimeda (Hendler et al. 1995). Burrowing individuals will frequently extend two to four arms across the sediment surface, while the disk and other arms remain inside the burrow.
The range of A. pulchella extends along both coasts of Florida, throughout the Florida Keys and Dry Tortugas, throughout the Gulf of Mexico, Cuba, Jamaica, Puerto Rico, the Windward and Leeward Islands of the Lesser Antilles, Tobago, Mexico, Belize, Brazil and Argentina (Hendler et al. 1995).
IRL Distribution: The distribution of A. pulchella within the IRL remains undocumented. However, this cryptic species likely occurs in soft sediments and seagrass beds throughout the IRL, especially in the southern lagoon.
Size: A. pulchella is one of several species of small brittle stars found in and around the IRL. The diameter of the central disk rarely exceeds 5 mm, and the five slender arms are only 40-50 mm long (Hendler et al. 1995).
Reproduction & Embryology: The small oocytes of A. pulchella measure only 0.65 mm in diameter, implying that the developing larvae have low yolk reserves. Therefore, A. pulchella is believed to have a planktonic, feeding larval stage (Hendler & Littman 1986).
Associated Species: A. pulchella has been collected along with several other brittle star species in sand, seagrass beds and mats of filamentous algae at Looe Key, Florida (Hendler et al. 1995).
Halpern JA. 1970. Growth rate of the tropical sea star Luidia senegalensis (Lamarck). Bull. Mar. Sci. 20: 626-633.
Hendler G & BS Littman. 1986. The ploys of sex: relationships among the mode of reproduction, body size and habits of coral reef brittle stars. Coral Reefs 5: 31-42.
Hendler G, Miller JE, Pawson DL & PM Kier. 1995. Sea stars, sea urchins, and allies: echinoderms of Florida and the Caribbean. Smithsonian Institution Press. Washington, D.C. 390 pp.
McNulty JK. 1961. Ecological effects of sewage pollution in Biscayne Bay, Florida: sediments and the distribution of benthic and fouling macro-organisms. Bull. Mar. Sci. Gulf Carib. 11: 394-447.
O’Gower AK & JW Wacasey. 1967. Animal communities associated the Thalassia, Diplanthera, and sand beds in Biscayne Bay. I. Analysis of communities in relation to water movements. Bull. Mar. Sci. 17: 175-210.
Shirley TC. 1982. The importance of echinoderms in the diet of fishes of a sublittoral rock reef. In: South Texas Fauna. Chapman BR & JW Tunnell (Eds.). 49-55. Caesar Kleberg Wildlife Research Institute, College of Agriculture, Texas A&I University, Knoxville, Texas.
Thomas LP. 1962. The shallow water amphiurid brittle stars (Echinodermata, Ophiuroidea) of Florida. Bull. Mar. Sci. Gulf Carib. 12: 623-694.
Aboral: In a direction away from the mouth; the part of the body opposite the mouth.
Anal Cone: In crinoids and echinoids, a fleshy projection bearing the anus at its apex; also known as an anal tube.
Apical System: In echinoids, a ring of specialized skeletal plates, including the genital plates and ocular plates; usually located on the highest point of the test.
Arm: In asteroids, crinoids, and ophiuroids, a movable, jointed ambulacral projection, distal to the disk or calyx that carries a radial branch of the water vascular system and the nervous system; sometimes called a ray.
Basket: One of several types of microscopic skeletal ossicles in holothuroids; minute cup-shaped ossicle, usually with four projections.
Button: One of several types of microscopic skeletal ossicles in holothuroids; minute ossicle with four perforations; may be smooth or knobbed.
Disk: The round or pentagonal central body region of ophiuroids and asteroids; see also Terminal Disk.
Distal: In a direction away from the center of the body; for example, toward the tip of the arm in asteroids or the tip of a spine in echinoids.
Dorsal: In echinoderms, this term is variously applied; in asteroids, ophiuroids and echinoids it usually refers to the surface of the body that is opposite the mouth, the surface that is uppermost; in holothuroids, with mouth and anus opposite ends of the cylindrical body, the uppermost surface is considered dorsal; in crinoids, the surface opposite the mouth in considered dorsal by convention, even though it is functionally the ventral (lower) side.
Echinulate: Something spiny or prickly, usually referring to the microscopic texture of a skeletal element such as a spine.
Hermaphrodism: A condition in organisms whereby one individual possesses both functional male and female reproductive structures; hermaphroditic individuals may express both sexes simultaneously, alternately, or sequentially.
Interambulacral Area: An oral or aboral section of the body lying between two ambulacra; in interradius; also known as an interambulacrum.
Interradial: Referring to interambulacral areas of the body; interradius and interradii also commonly used.
Oral: In a direction toward the mouth; a part of the body on the same surface as the mouth.
Oral Papillae: In ophiuroids, small plates at the edge of the mouth, attached to the edges of the jaw plate and/or to the aboral shield; may be variously shaped, from spine-like to scale-like.
Papillae: In holothuroids, specialized dorsal tube feet that lack a suckered tip; in ophiuroids, certain skeletal elements of the jaws or disk.
Papillate: Covered with papillae.
Papillose: Covered with papillae.
Pedicellariae: Small stalked or unstalked pincer-like organs on the body of asteroids and echinoids, used for defense and grooming.
Peltate: Shield-shaped; used to describe the tentacles of some holothuroids.
Perforated Plate: One of several types of microscopic skeletal ossicles in holothuroids; sieve-like and widespread; may also be found in other echinoderm classes, especially in juvenile individuals.
Periproct: In echinoids, a flexible region surrounding the anus, which consists of a membrane containing embedded plates and often bearing spines and pedicellariae.
Plates: One of several types of skeletal elements in echinoderms; tabular structures with a characteristic shape and a fixed position.
Primary Plates: The first-formed plates on the dorsal side of the disk; in ophiuroids, these are the central and five radial plates; in adults, they may form a rosette of scales near the center of the disk, or they may be separated by numerous secondarily developed scales.
Radial: In a direction toward the central axis of an arm or ambulacrum; a part of the body near an arm or ambulacrum.
Radial Shields: Pairs of plates on the dorsal surface of the ophiuroid disk, which lie near the base of each arm; usually relatively large and conspicuous, but may be hidden by granules or superficial scales.
Rods: One of several types of microscopic skeletal ossicles in holothuroids; commonly found as supporting structures in tentacles or tube feet.
Scales: One of several types of skeletal elements in echinoderms; flat, thin structures that are overlapping, tessellate, or haphazardly arrayed.
Sole: In some holothuroids, the flattened ventral part of the body, either covered with or surrounded by tube feet.
Spines: One of several skeletal elements in echinoderms; movable, articulating structures that are long, slender and attenuated.
Teeth: In ophiuroids, small plates or spines attached to the dental plate on the inner edge of the jaw, a series of them extending into the mouth; in echinoids, the five hard, sharp, and movable ossicles incorporated in Aristotle’s lantern; the term also refers to five movable ossicles that surround the anus of some holothuroids.
Tentacle Scales: Small, movable spines or scales, associated with ophiuroid tube feet, which are attached to the ventral arm plate and/or lateral arm plate; may cover the tentacle pores and protect the retracted tube feet.
Tentacles: In holothuroids, feeding structures in the form of highly modified tube feet arranged in a ring around the mouth.
Terminal Disk: Round portion on the end of the tube foot in many echinoderms; usually employed for attachment to substrates.
Tube Feet: Fluid-filled, fingerlike extensions of the water vascular system that protrude through the openings in the skeleton or between skeletal elements; muscles and nerves in the shaft of the tube feet control their movements; glands, and sometimes a muscular sucker, at the tip function in adhesion; specialized tube feet are used for locomotion, feeding, burrowing, respiration, and a combination of functions.
Ventral: In echinoderms, this term is variously applied; in asteroids, echinoids and ophiuroids, it is the surface of the body that carries the mouth; this surface is in contact with the substrate; in holothuroids, with mouth and anus at opposite ends of a cylindrical body, the ventral surface is lowermost, in contact with the substrate; in crinoids, the ventral surface carries the mouth and is functionally the uppermost surface.