Multiple origins of feeding head larvae by the Early Cambrian

2020 ◽  
Vol 98 (12) ◽  
pp. 761-776
Author(s):  
Richard R. Strathmann
Keyword(s):  
Larval Growth ◽  
The Body ◽  
Body Axis ◽  
Larval Feeding ◽  
Early Cambrian ◽  
Ciliary Band ◽  
Present Evidence ◽  
Multiple Origins ◽  
Front End ◽  
Adult Body

In many animals the head develops early, most of the body axis later. A larva composed mostly of the developing front end therefore can attain mobility and feeding earlier in development. Fossils, functional morphology, and inferred homologies indicate that feeding head larvae existed by the Early Cambrian in members of three major clades of animals: ecdysozoans, lophotrochozoans, and deuterostomes. Some of these early larval feeding mechanisms were also those of juveniles and adults (the lophophore of brachiopod larvae and possibly the ciliary band of the dipleurula of hemichordates and echinoderms); some were derived from structures that previously had other functions (appendages of the nauplius). Trochophores that swim with a preoral band of cilia, the prototroch, originated before divergence of annelids and molluscs, but evidence of larval growth and thus a prototrochal role in feeding is lacking for molluscs until the Ordovician. Feeding larvae that definitely originated much later, as in insects, teleost fish, and amphibians, develop all or nearly all of what will become the adult body axis before they begin feeding. On present evidence, head larvae, including feeding head larvae, evolved multiple times early in the evolution of bilaterian animals and never since.

Physiology of Larval Feeding

2018 ◽  
Keyword(s):  
Growth And Development ◽  
Marine Invertebrate ◽  
Larval Growth ◽  
Circulatory System ◽  
Future Research ◽  
Larval Feeding ◽  
Digestive Physiology ◽  
Larval Body ◽  
The Individual ◽  
Invertebrate Larvae

The functional properties of marine invertebrate larvae represent the sum of the physiological activities of the individual, the interdependence among cells making up the whole, and the correct positioning of cells within the larval body. This chapter examines physiological aspects of nutrient acquisition, digestion, assimilation, and distribution within invertebrate larvae from an organismic and comparative perspective. Growth and development of larvae obviously require the acquisition of “food.” Yet the mechanisms where particulate or dissolved organic materials are converted into biomass and promote development of larvae differ and are variably known among groups. Differences in the physiology of the digestive system (secreted enzymes, gut transit time, and assimilation) within and among feeding larvae suggest the possibility of an underappreciated plasticity of digestive physiology. How the ingestion of seawater by and the existence of a circulatory system within larvae contribute to larval growth and development represent important topics for future research.

scholarly journals Development of a new method for assessing otolith function in mice using three-dimensional binocular analysis of the otolith-ocular reflex

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shotaro Harada ◽  
Takao Imai ◽  
Yasumitsu Takimoto ◽  
Yumi Ohta ◽  
Takashi Sato ◽  
...  
Keyword(s):  
Eye Movement ◽  
Three Dimensional ◽  
Vertical Component ◽  
Inertial Force ◽  
Linear Acceleration ◽  
The Body ◽  
Body Axis ◽  
Gravitational Acceleration ◽  
Ocular Reflex ◽  
Translational Movement

AbstractIn the interaural direction, translational linear acceleration is loaded during lateral translational movement and gravitational acceleration is loaded during lateral tilting movement. These two types of acceleration induce eye movements via two kinds of otolith-ocular reflexes to compensate for movement and maintain clear vision: horizontal eye movement during translational movement, and torsional eye movement (torsion) during tilting movement. Although the two types of acceleration cannot be discriminated, the two otolith-ocular reflexes can distinguish them effectively. In the current study, we tested whether lateral-eyed mice exhibit both of these otolith-ocular reflexes. In addition, we propose a new index for assessing the otolith-ocular reflex in mice. During lateral translational movement, mice did not show appropriate horizontal eye movement, but exhibited unnecessary vertical torsion-like eye movement that compensated for the angle between the body axis and gravito-inertial acceleration (GIA; i.e., the sum of gravity and inertial force due to movement) by interpreting GIA as gravity. Using the new index (amplitude of vertical component of eye movement)/(angle between body axis and GIA), the mouse otolith-ocular reflex can be assessed without determining whether the otolith-ocular reflex is induced during translational movement or during tilting movement.

The Caenorhabditis elegans gene lin-44 controls the polarity of asymmetric cell divisions

Development ◽  
1994 ◽  
Vol 120 (5) ◽  
pp. 1035-1047 ◽  
Author(s):  
M.A. Herman ◽  
H.R. Horvitz
Keyword(s):  
Caenorhabditis Elegans ◽  
The Body ◽  
Body Axis ◽  
Nematode Caenorhabditis Elegans ◽  
Asymmetric Cell Divisions ◽  
Cell Divisions ◽  
Sister Cells

The generation and orientation of cellular and organismic polarity are fundamental aspects of development. Mutations in the gene lin-44 of the nematode Caenorhabditis elegans reverse both the relative positions of specific sister cells and the apparent polarities of these cells. Thus, lin-44 mutants appear to generate polar cells but to misorient these cells along the body axis of the animal. We postulate that lin-44 acts to specify the orientation of polar cells.

Head positioning control in a gravito-inertial field and in normal gravity

2004 ◽  
Vol 14 (4) ◽  
pp. 321-333
Author(s):  
Frédéric Sarès ◽  
Christophe Bourdin ◽  
Jean-Michel Prieur ◽  
Jean-Louis Vercher ◽  
Jean-Pierre Menu ◽  
...  
Keyword(s):  
Inertial Force ◽  
The Body ◽  
Body Axis ◽  
Positioning Control ◽  
Head Positioning ◽  
Subject Variability ◽  
Visual Frame ◽  
Vector Orientation ◽  
The Right ◽  
Within Subject Variability

The way in which the head is controlled in roll was investigated by dissociating the body axis and the gravito-inertial force orientation. Seated subjects (N = 8) were requested to align their head with their trunk, 30° to the left, 30° to the right or with the gravito-inertial vector, before, during (Per Rotation), after off-center rotation and on a tilted chair without rotation (Tilted). The gravito-inertial vector angle during rotation and the chair tilt angle were identical (17°). The subjects were either in total darkness or facing a visual frame that was fixed to the trunk. Both final error and within-subject variability of head positioning increased when the body axis and the gravito-inertial vector were dissociated (Per Rotation and Tilted). However, the behavior was different depending on whether the subjects were in the Tilted or Per Rotation conditions. The presentation of the visual frame reduced the within-subject variability and modified the perception of the gravito-inertial vector's orientation on the tilted chair. As head positioning with respect to the body and sensing of the gravito-inertial vector are modified when body axis and gravito-inertial vector orientation are dissociated, the observed decrease in performance while executing motor tasks in a gravito-inertial field may be at least in part attributed to the inaccurate sensing of head position.

scholarly journals PERTUMBUHAN LARVA DAN PRODUKSI BENIH IKAN KERAPU BEBEK Cromileptes altivelis Valenciennes, 1828 HASIL BUDIDAYA TURUNAN KE-3

2018 ◽  
Vol 10 (3) ◽  
pp. 589-600
Author(s):  
Regina Melianawati ◽  
Ni Wayan Widya Astuti ◽  
. Tridjoko
Keyword(s):  
Body Weight ◽  
Survival Rate ◽  
Seed Production ◽  
Larval Growth ◽  
The Body ◽  
Third Generation ◽  
Larval Body ◽  
Spine Length ◽  
The Third ◽  
Total Length

ABSTRAKKetersediaan induk dalam suatu usaha pembenihan memiliki peran yang sangat penting. Namun demikian, ketersediaan induk yang berasal dari alam sangat terbatas jumlahnya, sehingga perlu dilakukan penyediaan calon induk yang berasal dari hasil budidaya. Ikan kerapu bebek Cromileptes altivelis Valenciennes, 1828 turunan pertama (F-1) dan turunan kedua (F-2) sudah dapat diproduksi dari hasil budidaya, namun benih turunan ketiga (F-3) belum dapat diperoleh. Penelitian ini bertujuan untuk mendapatkan karakteristik morfologis dan pertumbuhan larva ikan kerapu bebek F-3 sebagai calon induk F-3, serta tingkat keberhasilan produksi benihnya. Pemeliharaan larva dilakukan dalam hatchery hingga larva menjadi benih. Parameter yang diamati meliputi panjang total dan panjang duri sirip larva, berat tubuh larva serta sintasan dan jumlah produksi benih. Hasil penelitian menunjukkan bahwa panjang total larva umur 5, 15, 25 dan 35 hari, masing-masing adalah 3,20±0,07; 4,42±1,11; 8,35±1,12 dan 12,51±3,23 mm. Duri sirip mulai terukur pada larva umur 15 hari. Berat larva umur 30 hari adalah 0,11±0,04 g. Pola pertumbuhan panjang total dan berat tubuh larva adalah eksponensial, sedangkan pola pertumbuhan duri siripnya adalah linier. Masa pemeliharaan larva hingga menjadi benih adalah ± 40 hari. Jumlah benih ikan kerapu bebek F-3 yang diproduksi dalam satu kali siklus pemeliharaan berkisar 440 hingga 2.300 ekor dari 50 ekor induk dan 3 kali siklus pemijahan dengan tingkat kelangsungan hidup 1,30% hingga 8,80%. Hasil penelitian ini mengindikasikan bahwa ikan kerapu bebek F-3 dapat diproduksi dari hasil budidaya seperti halnya pada F-1 dan F-2. ABSTRACTBroodstocks are the most important part of humpback grouper culture, but their availability in nature are limited. Therefore, it is necessary to produce broodstock candidates from culture. The first (F-1) and the second (F-2) generation of humpback grouper have already been produced but the third generation (F-3) production is still on the way. This study was conducted to find out morphological characteristic of the third generation (F-3) of humpback grouper larvae as the candidate of the third generation of broodstock, larval growth and the success rate of seed production. Larvae rearing was done in hatchery until larvae metamorphosed to be seeds. Observed variables including larval total length and spine length, larval body weight, survival rate and the juvenile productions. The study result showed the total length of 5, 15, 25 and 35 days old larvae were 3.20±0.07; 4.42±1.11; 8.35±1.12 and 12.51±3.23 mm, respectively. The spine began measured on 15 days old larvae. The body weight of 30 days old larvae was 0.11±0.04 g. The growth pattern of larval total length and body weight were exponential, while the growth of spine was linear. Rearing period from larvae to juveniles was 40 days. Number of F-3 seed production of humpback grouper produced from once rearing cycle range between 440 and 2,300 fish and the survival rate range from 1.30% up to 8.80%. Therefore, this study could indicate that seed of F-3 humpback grouper can be produced as those of F-1 and F-2.

scholarly journals How to attach the limb to the body axis

2010 ◽  
Vol 24 (S1) ◽  
Author(s):  
Johannes Streicher ◽  
Christine Pomikal
Keyword(s):  
The Body ◽  
Body Axis

scholarly journals Possible mechanisms of anosognosia: a defect in self–awareness

1998 ◽  
Vol 353 (1377) ◽  
pp. 1903-1909 ◽  
Author(s):  
◽  
K. M. Heilman ◽  
A. M. Barrett ◽  
J. C. Adair
Keyword(s):  
Population Study ◽  
Sensory Feedback ◽  
Large Population ◽  
The Body ◽  
Spatial Neglect ◽  
Self Awareness ◽  
Knowledge Of Results ◽  
Present Evidence ◽  
Sensory Deficits ◽  
Parallel Processes

Anosognosia of hemiplegia is of interest for both pragmatic and theoretical reasons. We discuss several neuropsychological theories that have been proposed to explain this deficit. Although for psychological reasons people might deny deficits, the denial hypothesis cannot account for the hemispheric asymmetries associated with this disorder and cannot explain why some patients might deny one deficit and recognize another equally disabling deficit. There is some evidence that faulty feedback from sensory deficits, spatial neglect and asomatognosia might be responsible for anosognosia in some patients. However, these feedback hypotheses cannot account for anosognosia in all patients. Although the hemispheric disconnection hypothesis is appealing, disconnection is probably only a rare cause of this disorder. The feedforward intentional theory of anosognosia suggests that the discovery of weakness is dependent on attempted action and some patients might have anosognosia because they do not attempt to move. We present evidence that supports this theory. The presence of one mechanism of anosognosia, however, does not preclude the possibility that other mechanisms might also be working to produce this disorder. Although a large population study needs to be performed, we suspect that anosognosia might be caused by several of the mechanisms that we have discussed. On the basis of the studies of impaired corporeal self–awareness that we have reviewed, we can infer that normal self–awareness is dependent on several parallel processes. One must have sensory feedback and the ability to attend to both one's body and the space where parts of the body may be positioned or acting. One must develop a representation of the body, and this representation must be continuously modified by expectations (feedforward) and knowledge of results (feedback).

New well-preserved scleritomes of Chancelloriida from early Cambrian Guanshan Biota, eastern Yunnan, China

2018 ◽  
Vol 92 (6) ◽  
pp. 955-971 ◽  
Author(s):  
Jun Zhao ◽  
Guo-Biao Li ◽  
Paul A. Selden
Keyword(s):  
New Species ◽  
Detailed Comparison ◽  
The Body ◽  
Single Element ◽  
Early Cambrian ◽  
Top Down ◽  
Middle Cambrian ◽  
Unusual Form ◽  
Guanshan Biota ◽  
A New Species

AbstractA large number of well-preserved chancelloriid scleritomes from the Guanshan biota, early Cambrian of Yunnan, China, are described as a new species,Allonnia tenuisn. sp., and provide solid evidence for the original appearance of these enigmatic animals, based on specimens compacted laterally and top-down. With the assistance of a flexible integument, chancelloriids, especiallyAllonniafrom early and middle Cambrian, may have had the ability to partially or completely expand and contract the body, which might have played an important role in feeding. A new metazoan with single-element spines,Nidelric gaoloufangensisn. sp., is also described. Preservation and affinity are discussed. Detailed comparison of the morphology of the body and spines of this metazoan indicate that it shares many similarities with chancelloriids, of which it may be an unusual form.UUID:http://zoobank.org/2708d95a-1fae-46fc-afea-9707ae97a4d7

scholarly journals Visual signal evolution along complementary color axes in four bird lineages

2019 ◽  
Author(s):  
Anand Krishnan ◽  
Avehi Singh ◽  
Krishnapriya Tamma
Keyword(s):  
Color Space ◽  
Dietary Factors ◽  
The Body ◽  
Color Variation ◽  
Visual Signals ◽  
Visual Signal ◽  
Relative Role ◽  
Chromatic Contrast ◽  
Present Evidence ◽  
Complementary Color

AbstractAnimal color patterns function in varied behavioral contexts including recognition, camouflage and even thermoregulation. The diversity of visual signals may be constrained by various factors, for example, dietary factors, and the composition of ambient environmental light (sensory drive). How have high-contrast and diverse signals evolved within these constraints? In four bird lineages, we present evidence that plumage colors cluster along a line in tetrachromatic color space. Additionally, we present evidence that this line represents complementary colors, which are defined as opposite sides of a line passing through the achromatic point (putatively for higher chromatic contrast). Finally, we present evidence that interspecific color variation over at least some regions of the body is not constrained by phylogenetic relatedness. Thus, we hypothesize that species-specific plumage patterns within these bird lineages evolve by swapping the distributions of a complementary color pair (or dark and light patches in one group, putatively representing an achromatic complementary axis). The relative role of chromatic and achromatic contrasts in discrimination may depend on the environment that each species inhabits.

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