scholarly journals The Histology and Activities of the Tube-feet of Echinocyamus pusillus

1959 ◽  
Vol s3-100 (52) ◽  
pp. 539-555
Author(s):  
DAVID NICHOLS
Keyword(s):  
Sea Urchin ◽  
Nerve Plexus ◽  
Asterias Rubens ◽  
Coelomic Epithelium ◽  
Sensory Cilia ◽  
Thin Walled ◽  
Postural Movement ◽  
Tube Feet

The histology of the suckered, buccal sensory, and respiratory tube-feet and their ampullae, where they occur, of the clypeasteroid sea-urchin Echinocyamus pusillus is described. Each suckered tube-foot possesses two sets of special muscles for attachment and detachment, a ring of mucous glands to assist in attachment, and a ring of sensory cilia. The stem retractors are in four columns, whose differential contraction provides the means of postural movement relative to the test. The ampullae of these tube-feet are exceedingly thin-walled, apparently musculo-epithelial, with anastomosing contractile elements. The canal between tube-foot and ampulla contains a swollen coelomic epithelium which may help to maintain the nerve relationships of the system. The activity of the suckered tube-feet is compared with that of the tubefeet of the starfish, Asterias rubens. The buccal tube-feet, larger than the suckered tube-feet, have large disks underlain by a thick nerve plexus supported by transverse fibres; a ring of sensory cilia surrounds the disk. They have no mucous glands and no suckers, and are presumably entirely sensory, probably both tactile (the cilia) and chemoreceptive (the disk). The respiratory tube-feet are thin-walled sacs, the walls consisting of an outer ciliated and an inner non-ciliated (coelomic) epithelium with cross-connexions for support; where the coelomic epithelium lines the pair of canals through the test it is heavily ciliated. In the specializations of its tube-feet this urchin is shown to share some features with the regular urchins and others with the spatangoids.

The Activities of the Tube Feet of Asterias Rubens L

1947 ◽  
Vol s3-88 (1) ◽  
pp. 1-14
Author(s):  
J. E. SMITH
Keyword(s):  
Forward Direction ◽  
The Other ◽  
Asterias Rubens ◽  
Ideal Form ◽  
First Time ◽  
Intrinsic Musculature ◽  
Tube Feet ◽  
Postural Muscles ◽  
The Ideal

1. An account is given of the muscular anatomy of the foot and ampulla of Asterias rubens. An intrinsic musculature of the sucker figured by Cuénot (1891) and Chadwick (1923) is shown not to be present; on the other hand, postural muscles responsible for orientating the podium, levator fibres which ‘cup’ the sucker, and radial fibres which flatten it are described and figured for the first time. 2. The role of the different muscle systems, the collagen connective tissue, and the fluid of the hydrocoel in protracting and retracting the foot, and in effecting the attachment and detachment of the sucker, is discussed. 3. Evidence is presented, to show that postural pointing of the foot is brought about by the contraction of a ring of muscles encircling the base of the podium. The orienting muscles are functionally, but not anatomically, distinct from the longitudinal fibres of the retractor sheath. 4. The ambulatory step is shown to comprise a series of linked phases of static posture and of movement. Each phase is characterized by the contraction of one member of each of the two opposing pairs of muscles engaged in the development of the step. The two pairs of muscles are (1) the anterior and posterior orienting fibres, and (2) the protractors and retractors of the foot. In its ideal form the step comprises four phases of static posture alternating with four movements. Each movement is ushered in by a reversal of the contraction-relaxation relationships of one of the two pairs of opposing muscle systems. Four such changes are possible and they occur in a sequence that ensures the orderly succession of the four movements of protraction, swing back, retraction, and swing forward, of which movements the idealized stepping cycle is composed. 5. The actual locomotory step departs from the ideal form in two respects: (1) it is liable to become disrupted by a delay in the initiation of the protraction or of the backswing movement, and (2) withdrawal of the podium occurs simultaneously with its re-orientation in the forward direction. It is pointed out that these variations are explicable on the assumption that, in the two series of opposing muscle pairs, the retractor fibres are more readily excited to contract than are their antagonists, and the anterior postural muscles than the posterior postural fibres.

Distribution and action of SALMFamide neuropeptides in the starfish Asterias rubens.

1995 ◽  
Vol 198 (12) ◽  
pp. 2519-2525 ◽  
Author(s):  
M R Elphick ◽  
S J Newman ◽  
M C Thorndyke
Keyword(s):  
Specific Antiserum ◽  
Body Parts ◽  
Pharmacological Effects ◽  
Asterias Rubens ◽  
Terminal Amino Acid ◽  
Cardiac Stomach ◽  
Terminal Amino ◽  
High Concentrations ◽  
Tube Feet ◽  
Terminal Amino Acid Sequence

The SALMFamides S1 and S2 are two structurally related neuropeptides that are present in starfish, and which share the C-terminal amino acid sequence SXLXFamide, where X is variable. To establish the distribution of S1 and S2 in starfish, we have raised antisera that recognise specifically the C-terminal pentapeptide sequence of either S1 or S2. Here we describe the production and characterisation of an S2-specific antiserum designated CLII. This antiserum, together with an S1-specific antiserum (BLII), has been used in a radioimmunoassay to measure S1 and S2 levels in extracts of body parts from the starfish Asterias rubens. High concentrations (250-400 pmol g-1) of both peptides were detected in the radial nerve cords of the nervous system and lower concentrations were detected in other body parts, including neuromuscular organs such as the tube feet, apical muscle and cardiac stomach. We have examined the pharmacological effects of S1 and S2 on the contractility of these three preparations. Neither S1 nor S2 influenced the tone of tube foot and apical muscle preparations but S2 caused relaxation of cardiac stomach preparations, antagonising the contracting action of acetylcholine.

scholarly journals Unique system of photoreceptors in sea urchin tube feet

2011 ◽  
Vol 108 (20) ◽  
pp. 8367-8372 ◽  
Author(s):  
E. M. Ullrich-Luter ◽  
S. Dupont ◽  
E. Arboleda ◽  
H. Hausen ◽  
M. I. Arnone
Keyword(s):  
Sea Urchin ◽  
Unique System ◽  
Tube Feet

Is the adhesive material secreted by sea urchin tube feet species-specific?

2011 ◽  
Vol 273 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Romana Santos ◽  
Patrick Flammang
Keyword(s):  
Sea Urchin ◽  
Adhesive Material ◽  
Species Specific ◽  
Tube Feet

scholarly journals Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6

2011 ◽  
Vol 278 (1723) ◽  
pp. 3371-3379 ◽  
Author(s):  
Michael P. Lesser ◽  
Karen L. Carleton ◽  
Stefanie A. Böttger ◽  
Thomas M. Barry ◽  
Charles W. Walker
Keyword(s):  
Differential Expression ◽  
Sea Urchin ◽  
Light Exposure ◽  
Light Sensitivity ◽  
Distal Portion ◽  
Pigment Cells ◽  
Functional Roles ◽  
Real Time Quantitative Pcr ◽  
Pax6 Protein ◽  
Tube Feet

All echinoderms have unique hydraulic structures called tube feet, known for their roles in light sensitivity, respiration, chemoreception and locomotion. In the green sea urchin, the most distal portion of these tube feet contain five ossicles arranged as a light collector with its concave surface facing towards the ambient light. These ossicles are perforated and lined with pigment cells that express a PAX6 protein that is universally involved in the development of eyes and sensory organs in other bilaterians. Polymerase chain reaction (PCR)-based sequencing and real time quantitative PCR (qPCR) also demonstrate the presence and differential expression of a rhabdomeric-like opsin within these tube feet. Morphologically, nerves that could serve to transmit information to the test innervate the tube feet, and the differential expression of opsin transcripts in the tube feet is inversely, and significantly, related to the amount of light that tube feet are exposed to depending on their location on the test. The expression of these genes, the differential expression of opsin based on light exposure and the unique morphological features at the distal portion of the tube foot strongly support the hypothesis that in addition to previously identified functional roles of tube feet they are also photosensory organs that detect and respond to changes in the underwater light field.

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