Burrows In Sand Research Articles

Cold temperatures as a source of stress: seasonality, sand burrowing and hemocyanin levels in Atlantic Canada sandy beach amphipods

Cold temperatures as a source of stress: seasonality, sand burrowing and hemocyanin levels in Atlantic Canada sandy beach amphipods

Staying high and dry: a unique nesting strategy for an insular iguana

Staying high and dry: a unique nesting strategy for an insular iguana

Liquid sand burrowing and mucus utilisation as novel adaptations to a structurally-simple environment in Octopus kaurna Stranks, 1990

Cephalopods are often celebrated as masters of camouflage, but their exploitation of the soft-sediment habitats that dominate the ocean floor has demanded other anti-predator strategies. Previous research has identified a small number of cephalopods capable of burying into sand and mud, but the need to directly access the water column for respiration has restricted them to superficial burying. Here, we report on the first known sub-surface burrowing in the cephalopods, byOctopus kaurna, a small benthic species that uses advanced sand-fluidisation and adhesive mucus for sediment manipulation. This burrowing strategy appears linked to easily fluidised sediments as shown in experimental trials in three size-grades of sediment. While the selective pressures that drove evolution of this behaviour are unknown, its identification enriches our understanding of the possible life-history traits and functional role of mucus in other benthic octopus species living in soft-sediment environments.

Phylogenetic systematics and biogeography of the sand crab families Albuneidae and Blepharipodidae (Crustacea : Anomura : Hippoidea)

Many unrelated crustaceans sharing a suite of convergent specialisations for a sand-burrowing existence have been placed in the anomuran family Albuneidae at one time or another. Although most of these non-albuneids have long since been reassigned to other families, recent molecular and morphological evidence has suggested a further split within the family between the Albuneidae (sensu stricto) and the Blepharipodidae. We used 173 morphological characters to test phylogenetic hypotheses about the monophyly of the Albuneidae and Blepharipodidae, as well as their constituent genera. We included 61 known species of albuneids and blepharipodids (including eight fossil species) and six outgroup species in five anomuran families. Analyses confirm that the Albuneidae and the Blepharipodidae are separate and monophyletic taxa that have convergently evolved similar adaptations to sand burrowing. Zygopa Holthuis, 1961 and Squillalbunea Boyko, 2002 are sister-taxa to the rest of the Albuneidae; all other Recent genera of albuneids are well supported and form two clades at the subfamily level. An Indo-Pacific origin for the Albuneidae is proposed and various scenarios regarding possible routes of dispersal are discussed.

Factors affecting retreat‐site selection by coppertail skinks (Ctenotus taeniolatus) from sandstone outcrops in eastern Australia

Abstract Coppertail skinks (Ctenotus taeniolatus) are medium‐sized diurnal lizards that are widespread in eastern Australia. Field surveys on sandstone outcrops in the Sydney region showed that these animals use available rocks non‐randomly: coppertails were found under large, sun‐exposed rocks on deep soil. Choice trials in the laboratory documented selection of retreat sites that were warm, with substrate preferences shifting in a diel cycle. Lizards selected retreats with rock substrates during the day but with sandy substrates at night. Rocky retreats attain higher temperatures during daylight hours, but burrows in sand beneath rocks may provide greater protection against ingress by nocturnal predators. During fieldwork we rarely found lizards under rocks with either ants or centipedes, suggesting that coppertails may avoid these predatory invertebrates. Tongue‐flick trials showed that the lizards could discriminate among common ant species based on chemosensory cues, but apparently could not detect centipede chemical cues. In experimental trials, the lizards did not avoid retreat sites scented by either ants or centipedes. Our data thus suggest that retreat‐site selection in coppertails is driven by abiotic cues (rock size, sun exposure and substrate type) that may confer fitness benefits in terms of thermoregulation and predator avoidance, with biotic cues playing a less important role.

EFFECTS OF SALINITY ON SAND BURROWING ACTIVITY, FEEDING AND GROWTH OF THE CLAMS MERETRIX LUSORIA

Mactra veneriformis, Ruditapes philippinarum, and Meretrix lusoria are dominant clams in Japanese tidal flats. Juveniles and adults of these species were reared in the laboratory and the effects of salinity on their sand burrowing activity and growth- and clearance-rates were examined. Juveniles of each species (shell length 10–16 mm) filtered water actively in the salinity range of 11.8–34.6 psu, with clearance rates not affected by salinity. The clams showed positive growth in the above salinity range, but growth rates were retarded at 11.8 psu, probably because of increased respiration at low salinity levels. In 6.1-psu seawater, adult Ma. veneriformis dug into the sand after a few days acclimation, Me. lusoria did not and R. philippinarum died. At 10.8 psu, adult Ma. veneriformis filtered water actively, Me. lusoria dug into the sand but did not filter water, and R. philippinarum neither dug into sand nor filtered water. These results indicate that the clam species examined are euryhaline but that the response to low-salinity water (≤11 psu) by adult clams (shell length 31–37 mm) differed among species: Ma. veneriformis is the most adaptable to low-salinity water, followed (in order) by Me. lusoria and R. philippinarum. These differences, however, are not consistent with the distribution patterns of these clam species in the Shirakawa tidal flat (Japan), where salinity varies spatially and temporally.

Water relations of the burrowing sandhill frog, Arenophryne rotunda (Myobatrachidae)

Arenophryne rotunda is a small (2-8 g) terrestrial frog that inhabits the coastal sand dunes of central Western Australia. While sand burrowing is a strategy employed by many frog species inhabiting Australia's semi-arid and arid zones, A. rotunda is unique among burrowing species because it lives independently of free water and can be found nocturnally active on the dune surface for relatively extended periods. Consequently, we examined the physiological factors that enable this unique frog to maintain water balance. A. rotunda was not found to have any special adaptation to reduce EWL (being equivalent to a free water surface) or rehydrate from water (having the lowest rehydration rate measured for 15 Western Australian frog species), but it was able to maintain water balance in sand of very low moisture (1-2%). Frogs excavated in the field were in dune sand of 4.4% moisture content, as a consequence of recent rain, which was more than adequate for these frogs to maintain water balance as reflected by their low plasma and urine osmotic concentrations. We suggest that in dry periods of the year, A. rotunda can achieve positive water balance by cutaneous water uptake by burrowing deeper into the substrate to where the percent water content is greater than 1.5%.

Transportation methods for restocking of juvenile sea cucumber, Holothuria scabra

The sandfish, Holothuria scabra, is a heavily exploited sea cucumber species. Minimising stress in the transportation of hatchery-produced sandfish juveniles to release sites is critical for successful restocking. Replicate groups ( n = 4) of 20 hatchery-produced juveniles (1–5 g) were held in plastic bags with oxygen under 6 transport durations (0, 2, 4, 8, 12 and 24 h), two media (water or saturated sponge), and two temperature regimes (ambient and cool). Subsequent deaths and sand burrowing of the groups in release chambers were monitored for 5 days. Juveniles eviscerated or died only in treatments at ambient temperature on sponge for 24 h. Oxygen consumption in bags was reduced at cool temperature. On the first day after release, the normal sand burrowing was suppressed in juveniles held for 12 and 24 h, suggesting that pre-release acclimation for 1 day at field sites would benefit restocking. After the initial ‘shock’ of transport, handling stress appeared to increase burrowing behaviour for several days. Hatchery-produced sandfish also proved hardy for transport in high densities (100 and 200 juveniles per bag) and transportation stress will be minimised in seawater held at cool, constant temperature.

Seasonal and Diel Changes in Thermal Tolerance of the Crayfish Orconectes rusticus, with Evidence for Behavioral Thermoregulation

The thermal tolerance (critical thermal maximum, CTM) of field-acclimatized Orconectes rusticus was examined on both a seasonal and diel basis. Seasonal changes in stream water temperature from 2.5 to 33.0°C caused a 10.8°C elevation (27.4 to 38.2°C) in mean CTM of adult O. rusticus. Juvenile O. rusticus exposed to a 6.9°C diel temperature change during summer altered their mean CTM by 1.2°C. Excessively high water temperatures (>39°C) in an isolated stream pool in southwestern Ohio during mid-July forced most O. rusticus to abandon the pool and dig burrows in sand and gravel beneath rocks near the shoreline. Mean water temperature in these burrows was >6°C cooler than that of the open pool. Orconectes rusticus physiologically adjusts its thermal tolerance to compensate for both seasonal and diel changes in its natural environment, but when temperatures change rapidly and become too high the species may search for or create cooler thermal refugia.

The burrow structure of the European rabbit (Oryctolagus cuniculus L.)

Samples of rabbit burrows were excavated and measured at four areas around Edinburgh. Of these, 31 burrows over 2 m long were analysed for internal structural relationships and the effect of soil composition and slope of the ground on their form. Seven variables were measured for each burrow—total length, number of entrance holes, number of junctions, number of ends, average length of sections between holes, junctions and ends, average depth and maximum depth. There are three main trends in burrow variation—size, an inverse relationship between relative number of holes and average depth, and an inverse relationship between average section length and relative number of junctions. Burrows in sand have relatively fewer holes and junctions, longer element lengths, a higher average depth and three times the enclosed volume per hole. Burrows dug into slopes have a higher average depth. Areas differed significantly in the relative number of holes and junctions, and average depth. It was concluded that an apparently complex structure could be summarized in terms of relatively few components. The chief of these, size, was largely independent of the soil and site characteristics, whereas the remaining two were dependent on the soil in which the burrow was dug. This may have implications for the ecology and behaviour of rabbits in different areas, and is relevant to the success of some rabbit control procedures such as burrow fumigation and warren ripping.

Notes On the Behavior of Euprymna Scolopes (Cephalopoda: Sepiolidae)

18 individuals of the sepiolid Euprymna scolopes were collected in Kaneohe Bay, Oahu, Hawaii. They were observed in the laboratory for a brief period. They were found to be non-gregarious and primarily nocturnal. It was possible to study feeding and defensive behavior. The species seems to prefer shrimps as prey. It is often cryptic. Among the adaptations for crypsis are color changes to match backgrounds (substrates), sand burrowing, and the cementing of sand grains to the back of an individual itself. The grains presumably are held in place by adhesive secretions of the skin. The captive animals also produced patterns which were conspicuous rather than cryptic. They were highly visible, occasionally intricate, combinations of light and dark. Some of them were distinctive. A single copulation was peculiar in certain respects (the spatial positions of the performers), but reminiscent of true cuttlefishes of the genus Sepia in other respects (color displays of both male and female). The phylogenetic implications of these observations are far from clear. On the behavioral evidence, Euprymna could be either a squid-like cuttlefish or a cuttlefish-like squid. It does not show any particular resemblance to Idiosepius, another supposed relative of Sepia.

Variations in the microclimate in rabbit warrens in semi-arid New South Wales

Rabbit burrows in three different habitats in an arid area showed characteristic variations and differences. Burrows in stony soil were generally cooler and more humid than burrows in sand and gravel soil. The temperature of the burrows in sand and gravel showed similar characteristics but the humidity in the gravel burrows was almost always significantly less than that of the sand burrows. Air and ground temperatures were significantly correlated but air and ground humidities showed a less significant correlation. Seasonal differences in microclimate within and between the three types of burrows were pronounced and are thought to cause differences in the survival of rabbits in arid areas.