Asteroidea Research Papers - Academia.edu (original) (raw)

In early 1992 the northern Pacific seastar, Asterias amurensis was identified from Tasmanian waters. It is possible that larvae may have been released in discarded ballast water from overseas ships. Each adult female may release up to... more

In early 1992 the northern Pacific seastar, Asterias amurensis was identified from Tasmanian waters. It is possible that larvae may have been released in discarded ballast water from overseas ships. Each adult female may release up to 19,000,000 eggs annually. The species is a serious predator of accessible marine fauna, particularly bivalve molluscs. Little is known of the impact of A. amurensis on its northern hemisphere habitat. The seastars appear to be thriving in Tasmanian waters and vast numbers have been observed around the Hobart waterfront. Research by the Tasmanian Museum includes survey s of present distribution and abundance of the seastar, data about its physico-chemical environment, aspects of its reproductive biology, and the species on which it preys. Future management of this pent in Australia may well depend on the information provided by this research [Asterias amurensis. ballast water introductions. [Echinodermata, Asteroidea, aquaculture, alien species, Tasmania. Australia.]

The response of Acanthaster planci or crown-of-thorns starfish (COTS) to intracoelomic injection of hypersaline solutions was investigated to establish its potential application as A. planci population control especially during an... more

The response of Acanthaster planci or crown-of-thorns starfish (COTS) to intracoelomic injection of hypersaline solutions was investigated to establish its potential application as A. planci population control especially during an outbreak. Adult A. planci when inverted had a normal righting response time (in seconds) of 163 ± 1 (mean ± SE; N ＝ 298). Injection of concentrated salt solutions led to negative effects on adult A. planci. The spines bent down, body collapsed and the starfish became comatose and died after 24-hours. The higher the salt concentration, the higher is the % comatose individuals. In addition, comatose specimens failed to recover with time. Mortality was highest at the highest treatment concentration with LC 90 of 285.3 and LC 99 of 383.2 ppt. The effects of time, salt concentration and its interaction(salt concentration x time) were significant (p ＝ 0.00). Theionic and osmotic disruption of the coelomic fluid canseriously affect physiological functions of the organismincluding neuromuscular activity. Thus, in the control of A. planci, concentrated salt solution can be used as a cheaper alternative to dry acid, acetic acid or m ammoniumhydroxide, all of which are expensive, may not be locally available and not environment friendly

The site of Bou Nemrou, in the Western Tafilalt (eastern Anti-Atlas, Morocco) is one of the very few Konservat-Lagerstätten known so far in the world to have yielded numerous remains of Late Ordovician softbodied fossils associated with... more

The site of Bou Nemrou, in the Western Tafilalt (eastern Anti-Atlas, Morocco) is one
of the very few Konservat-Lagerstätten known so far in the world to have yielded
numerous remains of Late Ordovician softbodied fossils associated with an abundant and diverse marine benthic fauna. This locality has also yielded several levels (starfish beds) extremely rich in exquisitely preserved echinoderms. Their remarkable preservation possibly results from the rapid, in situ burial of large, particularly dense, living communities (echinoderm meadows) by storm deposits. The Bou Nemrou starfish beds are dominated by eocrinoids and stylophorans, associated with crinoids, cyclocystoids, edrioasteroids, and ophiuroids. This composition is typical of the cool assemblages of the Mediterranean Province. The Bou Nemrou starfish beds may result from the opportunistic colonisation of the sea-floor by dense populations of echinoderms, during short phases of environmental disturbance.

Abstract – Asteroidea of Emilia-Romagna: first fossil record of Luidia sarsi Düben & Koren in Düben, 1845 (Echinodermata: Luidiidae). The skeletal ossicle morphology is diagnostic in the specific distinction of the genus Luidia Forbes,... more

Abstract – Asteroidea of Emilia-Romagna: first fossil record of Luidia sarsi Düben & Koren in Düben, 1845 (Echinodermata: Luidiidae). The skeletal ossicle morphology is diagnostic in the specific distinction of the genus Luidia Forbes, 1939 (Echinodermata: Asteroidea: Luidiidae): in this study, modern specimens from the Mediterranean Sea (Southern Malta) have been compared with Early Pleistocene fossils from Western Emilia Romagna. The fossil material under study consists of a single articulated and exceptionally preserved specimen from Taro River (Collecchio, Parma) and of isolated ossicles from Arda River (Castell’Arquato, Piacenza), Stirone River (San Nicomede, Parma), Gisolo River (Fidenza, Parma) and San Polo d’Enza (Reggio Emilia). In a recent study (Borghi & Bajo, 2009), this fossil material has been tentatively assigned to the species Luidia sarsi Düben & Koren in Düben, 1845. The ossicles from modern specimens have been taken off from the medial and proximal portions of the arms of mature and middle-sized specimens in order to avoid errors due to the great variation in ossicle morphology associated with other positions on the starfish. With regard to the skeletal ossicles, the main diagnostic characters of the species are inferomarginal plates with truncate adradial margin, ambulacral plates with an almost symmetrical body, adambulacral plates with three protruding articulations of spines and a large subtriangular smooth surface between the attachment areas of the muscles connecting the plate to the adjoining ambulacral and adambulacral ones. The slight differences observed between modern and fossil ossicles let us to confirm the diagnosis of the fossil specimens from Western Emilia-Romagna as Luidia sarsi. This is the first fossil record of the species. In all the examined Western Emilia localities, the remains of Luidia sarsi are associated to Astropecten irregularis pentachantus (Delle Chiaje, 1825). The last species has been interpreted by Dominici (2001) as a member of the Arctica islandica paleocommunity living at depths of 15–75 m in muddy bottoms of the inner shelf that occasionally experienced low oxygen levels. The taphonomic interpretation (Dominici, 2001) suggests that these konservatt-lagerstätten were obrution deposits caused by river floods entering shallow shelf settings and quickly smothering the resident echinoderms by mud clogging of the ambulacral system. We suggest that the asteroids were already stressed before burial by the lower salinity associated with the sediment-ladden, high-density flows entering the marine basin. This hypothesis is supported by the numerous endo-benthic echinoids of the genera Echinocardium and Schizaster from correlative outcrops, which were forced to emerge from the substrate before their burial.

Astropecten montalionis (Echinodermata: Asteroidea: Astropectinidae) was first described by Giuseppe Meneghini in 1852 (as Crenaster montalionis), the description following the donation by the municipality of Montaione (Tuscany, Central... more

Astropecten montalionis (Echinodermata: Asteroidea: Astropectinidae) was first described by Giuseppe Meneghini in 1852 (as Crenaster montalionis), the description following the donation by the municipality of Montaione (Tuscany, Central Italy) of a sandstone slab with an embedded fossil starfish specimen to the Museo di Storia Naturale dell’Università di Pisa. This slab was previously embedded in the floor of the main square of Montaione, in front of the church of S. Regolo, and for a long time it was eroded and damaged by pedestrian passage. Unfortunately, the specimen has never been figured in the literature. This fossil is here redescribed, taxonomically re-evaluated, and figured.

Проведен сравнительный анализ морфологии распластанных in vitro целомоцитов двух видов морских звезд Aphelasterias japonica и Patiria pectinifera (Echinodermata: Asteroidea) и гемоцитов двустворчатого моллюска Callista brevisiphonata... more

Проведен сравнительный анализ морфологии распластанных in vitro целомоцитов двух видов морских звезд Aphelasterias japonica и Patiria pectinifera (Echinodermata: Asteroidea) и гемоцитов двустворчатого моллюска Callista brevisiphonata (Mollusca: Bivalvia) с использованием ряда нелинейных параметров, включающих несколько типов фрактальных размерностей и лакунарностей. Визуально "хаотичные" формы распластанных in vitro гемоцитов и целомоцитов данных видов достоверно различаются по ряду нелинейных параметров, что позволяет численно описать морфологию клеток гемолимфы рассмотренных животных и высказать предположение о видоспецифичности биологических различий, влияющих на морфологию распластанной in vitro клетки.

Anasterias minuta is an oral-brooding sea star and one of the main predators of intertidal benthos in Patagonia, Argentina. The aims of this study were to: (1) assess the temporal pattern of feeding and brooding, (2) evaluate the effect... more

Anasterias minuta is an oral-brooding sea star and one of the main predators of intertidal benthos in Patagonia, Argentina. The aims of this study were to: (1) assess the temporal pattern of feeding and brooding, (2) evaluate the effect of body size, tidal height and temperature on feeding and brooding, (3) evaluate temporary changes in digestive and sexual organs and (4) investigate the relationships between the predatory and brooding activities. Females do not feed during the brooding period. Spawning proceeded during March. The brooding period was from March to November, with a maximum in May. The population feeding rate varied seasonally, with a maximum in December and a minimum in May. The feeding rate was positively related to water temperature and sea star size; but not with tidal height. An annual cycle exists for pyloric caeca weight in both sexes; lowest values were found during winter, due to brooding female starvation, and a possible decrease in feeding rate of non-brooding females and males. No inverse relationship was found between the pyloric caeca and gonad weights in females, but a lag of 1 month was observed in males, being the maximal pyloric caeca development before the maximum gonad weight, suggesting nutrient translocation.

FOSSIL ASTEROIDS FROM EMILIA (Northern Italy) Exceptionally preserved specimens of asteroids are described from the Pleistocene of the Stirone and the Taro Rivers, near Parma (Northern Italy). They belong to two species which are still... more

FOSSIL ASTEROIDS FROM EMILIA (Northern Italy)
Exceptionally preserved specimens of asteroids are described from the Pleistocene of the Stirone and the Taro Rivers, near Parma (Northern Italy). They belong to two species which are still living in the Mediterranean Sea: Astropecten irregularis pentacanthus and Luidia sarsi. The asteroids are associated to complete specimens of Ophiura ophiura and echinoids, within mass-mortality accumulations. The lethal events for the echinoderms likely consisted of salinity changes in shallow water environments, generated by river floods.