Species Description: Luidia senegalensis is an unusual member of the Asteroidea in that it possesses nine arms, which are long and thin. Members of this genus lack tube feet suckers and an anus (Brusca and Brusca 1990). The dorsal surface (back) of the nine-armed sea star is covered by close-set plates from square to irregular shape and fringed with spines. Plates that carry the spines are yellow and the spines are white. The square plates on the margin are cream-colored and the irregular plates along the mid-line are dark grey. Museum specimens are characterized by the dark midline. Ventrally the plates and spines are both white and the tube feet are transparent. The disk appears circular in outline in living individuals (Hendler et al. 1995).
Regional Occurrence: Luidia senegalensis occurs in subtropical and tropical east and west coasts of Florida as well as the Keys, the Greater and Lesser Antilles, and the coast of South America to southern Brazil (Hendler et al. 1995, Miller and Lawrence 1999). It occurs from the low tide line to 46 meters. The nine-armed sea star is found in calm lagoons in sandy or muddy sediments. In Southwest Florida, it can be found on quartz sand and hard shells (Hendler et al. 1995).
IRL Distribution: Luidia senegalensis is found sporadically in the Sebastian Inlet to the southern points of the Indian River Lagoon (Hendler et al. 1995).
Age, Size, Lifespan: Adult Luidia senegalensis can reach a total diameter of 30-40 cm. Individual arms of the adults range from 12-5 cm.
Abundance: The nine-arm sea star is reported to be more abundant in the coastal waters of southeastern Brazil (Pires 1992).
Reproduction: Luidia senegalensis reproduces annually with considerable seasonal variation among different populations. For example, in a population off of Naples, Florida, gonadal development was reported to begin in the winter, with the gonads reaching full size just before spawning in the late summer-early fall, while a population in Tampa began gonadal development in the fall followed by a spring spawning cycle (Miller and Lawrence 1999).
Embryology: Within 48 hours, the fertilized eggs of the nine-armed sea star develop into a feeding form called a bipinnaria larva. At 25 days the largest bipinnaria is approximately 1000 µm long and 350 µm wide and ready for metamorphosis. At this stage, it has two well developed ciliary bands and five pairs of binpinnaria arms. These larval structures are reabsorbed into the animal after metamorphosis (Komatsu et al. 1991).
Temperature: There are no specific studies addressing the temperature tolerances of larval or adult stages of Luidia senegalensis.
Salinity: There are no specific studies addressing the salinity tolerances of larval or adult stages of Luidia senegalensis.
Trophic Mode: Luidia senegalensis is a mobile soft bottom predator and scavenger, feeding on infauna and detritus. It will ingest sand and mud, straining the soft sediment through oral spines that retain prey such as small mollusks, crustaceans and brittle stars. When L. senegalensis is buried, it will evert its stomach to feed on detritus (Hendler et al. 1995).
Associated Species: Specimens of the nine-arm sea star collected from the Fort Pierce Inlet in the Indian River Lagoon have a dark brown, commensal polychaete worm, Podarke obscura Verrill, living in the ambulacral groove. Several worms can be found on one adult L. senegalensis (Miller and Lawrence 1999).
Brusca RC and GJ Brusca. 1990. Invertebrates. Sinauer Associates, Inc., Sunderland, MA pp. 804.
Hendler G, Miller JE, Pawson DL, and PM Kier. 1995. Sea Stars, Sea Urchins, and Allies. Smithsonian Institution Press, Washington, D. C. pg. 69-71.
ITIS. Integrated Taxonomic Information System. Available online.
Komatsu M, Chia F-S, and R Koss. 1991. Sensory neurons of the bipinnaria larva of the sea star, Luidia senegalensis. Invertebrate Reproduction and Development. 19:203-211.
Miller SR and JM Lawrence. 1999. Gonad and pyloric caeca production nine-armed starfish Luidia senegalensis off the southwest Florida gulf coast during the annual reproductive cycle. Bulletin of Marine Science 65:175-184.
Pires AMS. 1992. Structure and dynamics of benthic megafauna on the continental shelf offshore of Ubatuba, southeastern Brazil. Marine Ecology Progress Series 86:63-76.
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.