Clyde Freeman Herreid

Hypoxia in invertebrates

Abstract o 1. Oxygen consumption (MO2) may be independent or dependent upon environmental partial pressure of O2 (PIO2). The degree of regulation depends upon the species, the physiologic state of the individual, as well as temperature and salinity of the environment. 2. A model of gas exchange is presented where MO2 depends upon the PO2 gradient between the environment and mitochondria and on the O2 conductance (GT) through the animal: MO2=Gr (PiO2−PmO2). 3. Regulators compensate for a fall in PIO2 by increasing O2 conductance such as via increased ventilation (VG) or circulation. Different strategies are evident by examining changes in VG and O2 extraction and percent utilization. 4. Three types of conformers are designated depending upon the extent to which they compensate anaerobically for a drop in P1O2. 5. Five types of recovery patterns from hypoxia are designated depending upon the nature of the O2 debt.

Metabolism of land snails (Otala lactea) during dormancy, arousal, and activity

Abstract 1. 1. Otala lactea are induced to arouse from dormancy at 20°C by increasing the relative humidity to 85%. The metabolic rate rises just prior to emergence. 2. 2. Oxygen consumption/g of dormant and active snails is related to body wt. The least squares regression lines relating the two variables are as follows: log V O 2 = 1.99 − 1.01 log W for dormant snails log V O 2 = 2.07 − 0.43 log W for active snails log V O 2 = 2.32 − 0.47 log W for peak activity where VO2 is μl O2/g × hr and W is body wt in g. 3. 3. Peak metabolic rate is on the average 6 times higher than the average dormant rate. 4. 4. The slope relating metabolism to body wt appears to differ in dormant and active snails. Since small snails have higher metabolic rates/g than large, their potential length of dormancy should be correspondingly reduced.

Cockroaches on a treadmill: aerobic running

Abstract Five species of cockroach were tested on a miniature treadmill at three velocities as O2 consumption ( V O 2 ) was measured: Gromphadorhina chopardi, Blaberus discoidalis, Eublaberus posticus, Byrsotria fumagata and Periplaneta americana. All cockroaches showed a classical aerobic response to running: V O 2 increased rapidly from a resting rate to a steady-state ( V O 2ss ): t 1 2 on-response varied from under 30 s to 3 min. Recovery after exercise was rapid as well; t 1 2 off-response varied from under 30 s to 6 min. These times are faster or similar to mammalian values. V O 2 varied directly with velocity as in running mammals, birds and reptiles. V O 2 during steady-state running was only 4–12 times higher than at rest. Running is energetically much less costly per unit time than flying, but the cost of transport per unit distance is much more expensive for pedestrians. The minimal cost of transport (Mrun), the lowest V O 2 necessary to transport a given mass a specific distance, is high in cockroaches due to their small size. The new data suggest that insects may be less economical than comparable sized vertebrates.

Energetics of Pedestrian Arthropods

Study of the energetics of locomotion has existed for over 50 years (e.g., Hill, 1927; Fenn, 1930). Understandably, most of the interest has been focused on human and mammalian modes of travel. Little attention has been paid to the study of energetics of invertebrates except for the fine work on insect flight beginning with Chadwick and Gilmour (1940) on fruit flies, followed by investigations on locusts (Krogh and Weis-Fogh, 1951) and leading to the more recent publications (e.g., Vogel, 1966; Weis-Fogh, 1967; Bartholomew and Casey, 1977; Kokshaysky, 1977). The general absence of information on terrestrial and aquatic locomotion in arthropods is unfortunate since most phyla use these methods of travel. Moreover, arthropods should be especially interesting to compare with vertebrates, for they have radically different modes of respiration (varying from tracheae to gill-breathing to book lungs), circulation (open circulatory systems with or without respiratory pigments such as hemocyanin), and leg numbers (ranging from the legless larvae, the 6-legged pattern of insects, 8-legged pattern of arachnids and crabs to the multilegged centipedes and millipedes).

Radiometric Determination of Feather Insulation and Metabolism of Arctic Birds

T IRADITIONALLY, the insulation value for fur or feathers of animals has been obtained by determining heat flow through dried skins or by assuming that the surface temperatures of feathers or fur approximate ambient conditions (Scholander et al., 1950; Hammel, 1955; Hart, 1956; West, 1962). Thermocouples have been used to measure thermal gradients in the fur of red-backed voles (Griffin and Hammel, 1956), but this technique is difficult and determines heat loss from only a few body areas. The validity of these data and calculations has not been established because of the difficulty in determining the surface temperatures of fur or feathers in living, unrestrained animals. The feasibility of determining surface temperatures for the plumage of unrestrained birds with an infrared radiometer was suggested by the successful application of this instrument to measure skin temperatures of nude men (Veghte and Solli, 1962). Thermograms of birds

Temperature Regulation, Temperature Preference and Tolerance, and Metabolism of Young and Adult Free-Tailed Bats

Microchiroptera can drop to lower levels (Eisentraut, 1934; Hock, 1951; Reeder and Cowles, 1951). Although there has been some suggestion that Microchiroptera are not always so temperature labile (Reeder and Cowles, 1951; Morrison, 1959; Eisentraut, 1960), a detailed study of the temperature response of a species which does not hibernate was lacking. Thus a study on the migratory species, the Mexican free-tailed bat, Tadarida brasiliensis mexicana (Saussure), was initiated. This bat is distributed throughout southwestern United States and annually 1 This work was supported by grant E1040 from the National Institutes of Health and conducted at Pennsylvania State University. The author is grateful to Dr. David E. Davis for his advice and support and to Dr. Harold B. Hitchcock, Samuel Harbo, and Janet Herreid for their assistance.

Flight Patterns of Bats

The time of the evening emergence and return of Tadarida brasiliensis mexicana is correlated with light conditions. The average emergence time was 11 minutes after sunset. Emergence was earlier on cloudy evenings. A literature search revealed three annual emergence patterns in bats: (1) species without seasonal differences in emergence time in relation to sunset, (2) species which leave relatively later in the spring and fall and (3) species which emerge relatively earlier in the spring and fall. Feeding flights of Tadarida were either diffuse where there was little group integrity or serpentine where the bats flew in a column. Serpentine flights occurred earlier in relation to sunset than did diffuse. The average time away from the cave was 3 hours 48 minutes. Calculations based on measured flow rate and flight duration indicate that all bats in a large population cannot leave the cave each night.

Blood vascular system of the sea cucumber, Stichopus moebii

Stichopus moebii, a sea cucumber, has a closed circulatory system which is unique in its degree of development for the phylum Echinodermata. The gross anatomy, histology and fine structure of the system were studied. Blood vessels consist of a coelomic surface of ciliated epithelium, a layer of muscle and nerve cells, followed by connective tissue and luminal lining of endothelium. Basically the blood vascular system consists of two major vessels running parallel to the gut: the dorsal vessel pumps colorless blood via the vessels within the walls of the intestine into the ventral vessel. There are two specialized areas of the circulation: (1) At the upper small intestine 120 to 150 muscular single‐chambered hearts pump blood from the dorsal vessel into a series of intestinal plates. (2) At the lower region of the small intestine the vasculature is associated with the left respiratory tree. Blood passing from the dorsal pulmonary vessel can take two routes to the gut, it either passes through myriads of minute respiratory shunt vessels entangled with the respiratory tree or it passes through a unique follicle network consisting of tiny channels periodically dilated into chambers filled with iron deposits, necrotic cells and developing coelomocytes.

Gender differences in student performance in large lecture classrooms using personal response systems (‘clickers’) with narrative case studies

This study investigated gender differences in science learning between two pedagogical approaches: traditional lecture and narrative case studies using personal response systems (‘clickers’). Thirteen instructors of introductory biology classes at 12 different institutions across the USA and Canada used two types of pedagogy (Clicker Cases and traditional lecture) to teach eight topic areas. Three different sets of multiple regression analysis were conducted for three separate dependent variables: posttest score, change in score from posttest to final, and transfer score. Interactions between gender and pedagogical approach were found across the three analyses. Women either performed better with Clicker Cases, or about the same with either instructional method, but men performed markedly better with lectures in most topic areas. Our results suggest that men and women experience two pedagogical approaches—Clicker Cases and lectures—differently, and that Clicker Cases are more favorable for women than for men.

Color change in exercising crabs: evidence for a hormone

SummaryThree species of crabs exercised to fatigue showed a blanching and/or reddening of the body and legs. InUca pugilator this effect was due to white and red pigment dispersion in the leucophores and erythrophores, respectively, and a black pigment concentration in the melanophores. The pigment movements were induced by factor(s) present in the blood of exercisingUca; blood (hemolymph) removed from an exercised crab and injected into the isolated leg segment of another individual cause pigment movements similar to those seen in intact fatigued crabs. The blood of exercisedUca also caused similar chromatophore changes in isolated leg segments of the crabSesarma cinereum. The evidence suggests that blood-borne factor(s) related or identical to chromatophorotropins are released during vigorous exercise in crabs. We speculate that the effects of these exercise factor(s) are secondary to possible effects on carbohydrate and lipid metabolism associated with exercise.