Wyniki wyszukiwania - BazTech

1

Asteroidea from the lower Kimmeridgian of Wapienno/Bielawy, Kuyavia region, north-central Poland

Loba Michał, Radwańska Urszula

Acta Geologica Polonica

|

2022

|

Vol. 72, no. 1

89--106

EN

A relatively rich assemblage of starfish is recognised from the talus facies of an Upper Jurassic (lower Kimmeridgian) biohermal, sponge-cyanobacterial build-up from the Wapienno/Bielawy succession exposed in a salt-dome anticline in Kuyavia region, north-central Poland. The paper presents 8 taxa belonging to 4 genera (one new to science): Boxaster gen. nov., Noviaster Valette, 1929, Tylasteria Valette, 1929, Valettaster Lambert, 1914, and 4 families: Astropectinidae Gray, 1840, Goniasteridae Forbes, 1841, Sphaerasteridae Schöndorf, 1906 and Stauranderasteridae Spencer, 1913. Only a very few representatives of some of these taxa have formerly been reported from the Jurassic of Poland. Two species are new: Valettaster planus sp. nov. and Boxaster wapienensis gen. et sp. nov. The Jurassic starfish assemblage recognised from the Wapienno/Bielawy succession is interpreted as an offshore starfish fauna with the admixture of allochtonous shallow-water taxa. The lithology of the source deposits indicates their transport by storm agitation and/or mass movements. This fact strongly influenced the preservation state, all collected plates being disarticulated and most of them abraded.

2

Food selection of Antarctic sea star Odontaster validus (Koehler) : laboratory experiments with food quality and size

Kidawa A.

Polish Journal of Ecology

|

2009

|

Vol. 57, nr 1

139-147

EN

According to Optimal Foraging Theory a consumer should select its diet in order to maximise net energy intake per unit of foraging time. Therefore, the Antarctic scavenging sea star Odontaster validus can be expected to choose food items of high profitability and ignore those of low profitability. Laboratory experiments with agar models of food items were performed to investigate the foraging behaviour and food selectivity of O. validus. Freshly caught sea stars were first fed with fish meat to minimize differences in their feeding status and then starved for 2 and 4 weeks. Sea stars were divided into three size groups (small - radius 1-3 cm, medium - radius 3-4 cm, large - radius 4-5.5 cm). Agar food items of different quality (low - 1.2 kJ, medium - 2.5 kJ, high - 4.1 kJ) and size (small - 8 cm[^3] and large - 64 cm[^3]) were utilized in the experiments. Sea stars were individually presented with food items placed on the aquarium bottom, and their behaviour (number and type of ivestigated food items, time needed for final choice) was observed for 30 minutes. Starved individuals preferentially selected more profitable food items as is predicted by Optimal Foraging Theory. Choice of food item was probably mediated by contact chemoreception. Starvation time and sea star size had significant impact on selectivity. Mean number of food items of different quality investigated by sea stars starved for 2 weeks was higher then in sea stars starved for 4 weeks. Low quality food items were mostly chosen by small sea stars, and never by large individuals starved for 2 weeks. Sea stars O. validus were also capable of distinguishing between small and large food items. Final choice made by sea stars presented with food items of differing size depended on their size with large and medium individuals choosing mostly large food items. Sea stars starved for 2 weeks chose higher proportion of large food items than individuals starved for 4 weeks. Such strategy in accordance with Optimal Foraging Theory allows for flexibility in O. validus feeding behaviour and enables this species to survive in harsh marine environment, where food resources accessible during the Antarctic winter are scarce and unpredictable in space and time.

3

Aberrantne rozgwiazdy z rodzaju Sphaeraster Quenstedt, 1875, w profilu oksfordu Wapienno/Bielawy na Kujawach

Radwańska U.

Volumina Jurassica

|

2003

|

Vol. 1, no. 1

63-70