The behavioral responses of the fiddler crab, UCA PUGILATOR, to ionizing irradiation

Thesis (M.A.)--Boston University. Note: Page 24 is missing.Many animals, invertebrates as well as vertebrates, have demonstrated an ability to somehow sense ionizing irradiation. This recognition is often apparent by a behavioral response which can be correlated with the x-ray stimulus in some way. The fiddler crab, Uca pugilator, was found to exhibit a behavioral response to ionizing irradiation. When the x-ray machine was turned off, the animal would respond instantaneously by a marked hesitation in its general movement after which it would resume its normal activity. This response suggests the animal's ability to somehow be aware of irradiation. Previous work in this area suggested that the photoreceptors were the primary site of stimulation. The fiddler crab's photoreceptors, located at the ends of protruding eye-stalks, are particularly easily excised. When the eye stalks were rer1oved, the response to x-rays was no longer evident. A parallel series of experiments were done with ltght as the stimulus. With intact eyestalks, the animal showed the same off response, and with the eyestalk removed, the subject exhibited no such response. The possibility of a direct stimulation of nervous structures as well as that of an indirect activation by the x-ray evoked release of bioactive substances is discussed. After considering the sinus gland, which was also removed along with the photoreceptors, as a possible site of x-ray reception, a strong implication that the photoreceptors are the primary locus of x-ray sensitivity in the fiddler crab was stated. The marked dose rate dependency of the animal's response to x-rays was noted, and a possible explanation was suggested

A four stage evolution of the White Channel gravel: Implications for stratigraphy and palaeoclimates

Although the White Channel gravel (WCG) of the Klondike district, Yukon, contains gold placers which have been exploited for over a century, few sedimentological studies have been undertaken. This study reports a four stage evolution of the WCG, comprising: i. An initial downcutting period which preferentially retained gold particles on the base of the strath. ii. An aggradational stage in which gold concentration occurred within sedimentary features. iii. A lacustrine layer representing a depositional hiatus. iv. A final, more rapidly aggrading fluvial stage. Identification of the lacustrine layer has clarified the evolution of the WCG depositional fluvial systems. Architectural element analysis and detailed sedimentological observations have been synthesized to gain a clearer understanding of the spatial variations within the WCG. Additionally, the identification of plant species from pollen within the lacustrine layer provides irrefutable evidence that the Klondike district was at least 7°C warmer during the Pliocene compared to the present

Second Location for Two Rare Odonata in Ohio, \u3ci\u3eNannothemis Bella\u3c/i\u3e and \u3ci\u3eLadona Julia\u3c/i\u3e, (Odonata: Libellulidae) Discovered at Singer Lake Bog, Summit County, Ohio.

Previously the dragonflies (Odonata, Libellulidae) Ladona julia and Nannothemis bella were known in Ohio from only one extant population each: L. julia from extreme northwest Ohio in Williams County and N. bella from west-central Ohio in Champaign County. During the summer of 2000 populations of each of these species were found in close proximity to each other at Singer Lake, a wetlands complex in southern Summit County in northeastern Ohio. This new location is also home to a population of another rare Ohio dragonfly, Dorocordulia libera (Odonata, Corduliidae) that was discovered during 1999. The Singer Lake wetlands are proving to be a very significant habitat for Ohio Odonata

Wings Over the Forests

As the winter rains and snows subside and the sun rises higher in the Northem skies to shorten the long shadows, Weyerhaeuser\u27s flying foresters ready their steel horses and flex their wings, for a new season is about to be born

Aberrant Wing Pigmentation in \u3ci\u3eLibellula Luctuosa\u3c/i\u3e Specimens From Ohio

Over the past few years we obtained three female Libellula luctuosa specimens, all collected in northeast Ohio, which exhibited unusually reduced wing pigmentation. The individuals were extremely difficult to identify as most keys rely heavily upon wing pigmentation for identification of many Libellula species. A description of this aberrant wing pigmentation and a photograph are provided