Echidnas of the Sea: The Defensive Behavior of Juvenile and Adult Crown-of-Thorns Sea Stars

2021 ◽  
pp. 000-000
Author(s):  
Dione J. Deaker ◽  
Regina Balogh ◽  
Symon A. Dworjanyn ◽  
Benjamin Mos ◽  
Maria Byrne
Keyword(s):  
Defensive Behavior ◽  
Sea Stars

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

The role of serotoninergic brain structures in neurotensin influence mechanism on defensive behavior in rats

2007 ◽  
Author(s):  
N. P. Shugalev ◽  
A. V. Stavrovskaja ◽  
S. Olshanskij ◽  
G. Hartmann ◽  
L. Lenard
Keyword(s):  
Defensive Behavior ◽  
Brain Structures ◽  
Influence Mechanism

scholarly journals Sea stars generate downforce to stay attached to surfaces

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mark Hermes ◽  
Mitul Luhar
Keyword(s):  
Body Shape ◽  
Control Volume ◽  
Water Channel ◽  
Morphological Plasticity ◽  
The Body ◽  
Sea Star ◽  
Sea Stars ◽  
Hydrodynamic Loads ◽  
Spherical Dome ◽  
Star Models

AbstractIntertidal sea stars often function in environments with extreme hydrodynamic loads that can compromise their ability to remain attached to surfaces. While behavioral responses such as burrowing into sand or sheltering in rock crevices can help minimize hydrodynamic loads, previous work shows that sea stars also alter body shape in response to flow conditions. This morphological plasticity suggests that sea star body shape may play an important hydrodynamic role. In this study, we measured the fluid forces acting on surface-mounted sea star and spherical dome models in water channel tests. All sea star models created downforce, i.e., the fluid pushed the body towards the surface. In contrast, the spherical dome generated lift. We also used Particle Image Velocimetry (PIV) to measure the midplane flow field around the models. Control volume analyses based on the PIV data show that downforce arises because the sea star bodies serve as ramps that divert fluid away from the surface. These observations are further rationalized using force predictions and flow visualizations from numerical simulations. The discovery of downforce generation could explain why sea stars are shaped as they are: the pentaradial geometry aids attachment to surfaces in the presence of high hydrodynamic loads.

scholarly journals Entangling the Enemy: Ecological, Systematic and Medical Implications of Dermestid Beetle Hastisetae

Insects ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 436
Author(s):  
Enrico Ruzzier ◽  
Marcin Kadej ◽  
Andrea Di Giulio ◽  
Andrea Battisti
Keyword(s):  
Defensive Behavior ◽  
Digestive System ◽  
Living Environment ◽  
Morphological Features ◽  
Allergic Reactions ◽  
Stored Products ◽  
Genus Level ◽  
Basic Concepts ◽  
Source Of Information ◽  
Fine Morphology

Hastisetae are modified setae typical of Dermestidae Megatominae and are a primary defensive tool of both larvae and pupae against invertebrates and possibly vertebrates. Given their unique morphological features, hastisetae have recently been suggested as an additional character useful for larvae identification and possible source of information to clarify the systematics of Megatominae. Hastisetae are also recognized as important contaminants of stored products, work and living environment; in particular, the exposure to hastisetae seems to cause allergic reactions and the insurgence of skin rashes, asthma, conjunctivitis, and digestive system inflammation in humans. Starting from these basic concepts, the present paper provides a detailed description of the hastisetae of some Megatominae. Fine morphology of external and internal microstructures of the hastisetae is shown and compared at the genus level. The insertion on integument, the pedicel, the shaft, and the apical head are illustrated in detail, and the first observations of active defensive behavior based on hastisetae are recorded and presented. Possible implications to the systematics of skin beetles are proposed based on the results of the study.

Patiriella pseudoexigua (Asteroidea: Asterinidae): a cryptic species complex revealed by molecular and embryological analyses

2003 ◽  
Vol 83 (5) ◽  
pp. 1109-1116 ◽  
Author(s):  
Michael W. Hart ◽  
Maria Byrne ◽  
Sheri L. Johnson
Keyword(s):  
Dna Sequences ◽  
Original Description ◽  
Sensu Stricto ◽  
Genetic Distances ◽  
New Combination ◽  
Sea Stars ◽  
Planktonic Larva ◽  
Closely Related Species ◽  
Planktonic Larvae ◽  
Cryptic Species Complex

Cryptic lineages were identified within a morphologically uniform group of sea stars distributed from Australia to Japan. Among eight populations, all of which have been referred to Patiriella pseudoexigua, we found seven unique mitochondrial DNA sequences clustered into four distinct lineages. These four lineages formed a monophyletic group in which sister clades were separated by small genetic distances but could be differentiated from each other on the basis of reproductive differences. The four lineages thus appear to be separate but very closely related species. Examination of reproduction in several Queensland populations revealed that one population (Statue Bay) consisted of hermaphroditic intragonadal brooders with live-born offspring while other populations (Townsville, Bowen, Airlie Beach) consisted of dioecious free-spawners with a planktonic larva. The brooded larvae from central Queensland populations closely resembled brooded embryos and larvae of a Japanese lineage, while the planktonic larvae from northern Queensland were similar to the original description of planktonic larvae from a Taiwan population. However, each of the viviparous lineages was more closely related to a lineage with planktonic larval development than the viviparous lineages were to each other. Patiriella pseudoexigua thus comprises at least four species with different reproductive phenotypes in which viviparous brooding appears to have evolved in parallel. Based on previous taxonomic work we propose the following names for these four lineages: the dioecious free-spawner from northern Queensland (including the P. pseudoexigua type locality) is P. pseudoexiguasensu stricto; the viviparous brooder from central Queensland is undescribed and here referred to as Patiriella sp. nov; the dioecious free-spawner from Taiwan is temporarily referred to as Patiriella sp. (a senior name for this species may be P. pentagonus); and the hermaphrodite brooder from Japan should be raised to specific status and referred to by the new combination P. pacifica.

Paraventricular nucleus CRH neurons encode stress controllability and regulate defensive behavior selection

2020 ◽  
Vol 23 (3) ◽  
pp. 398-410 ◽  
Author(s):  
Núria Daviu ◽  
Tamás Füzesi ◽  
David G. Rosenegger ◽  
Neilen P. Rasiah ◽  
Toni-Lee Sterley ◽  
...  
Keyword(s):  
Paraventricular Nucleus ◽  
Defensive Behavior ◽  
Behavior Selection
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