Tube Feet Research Articles

Cloning and gene expression of allograft inflammatory factor-1 (AIF-1) provide new insights into injury and bacteria response of the sea cucumber Apostichopus japonicus (Selenka, 1867)

Allograft inflammatory factor-1 (AIF-1) is an interferon (IFN)-γ-inducible Ca2+-binding cytokine that associates with the immune defense and inflammatory response. In this study, we reported AIF-1 gene in sea cucumber Apostichopus japonicus (AjAIF-1). The full-length cDNA of AjAIF-1 is 1541 bp with an open reading frame (ORF) of 477 bp encoding 158 amino acids. Two EF-hand Ca2+-binding motifs were found in the deduced AjAIF-1. AjAIF-1 was widely expressed in all tested tissues (body wall, intestine, respiratory tree, tube feet, coelomocytes and longitudinal muscle), with the highest expression in respiratory tree. After Vibrio splendidus challenge and physical injury, AjAIF-1 transcripts were significantly upregulated in coelomocytes. The mRNA expression level of AjAIF-1 in coelomocytes reached to the highest value at 4 h (3.38-folds vs. the PBS control, P < 0.05) post injection. After papilla injury, the mRNA level of AjAIF-1 in coelomocytes was upregulated, and its peak value was found at 4 h (3.88-folds vs. the control, P < 0.05). These results indicated that 1) AjAIF-1 sensitively responds to pathogen infection; 2) AjAIF-1 is involved in acute inflammatory response. Our findings gain general information about the role of AjAIF-1 in the innate immunity of A. japonicus.

Benthodytes violeta, a new species of a deep-sea holothuroid (Elasipodida:Psychropotidae) from Mar del Plata Canyon (south-western Atlantic Ocean).

A new species of elasipodid holothuroid, Benthodytes violeta sp. nov., is described from the Mar del Plata Canyon off Buenos Aires Province (around 38ºS-54ºW). It was taken at four locations at depths ranging from 1500 to 1950 m. This new species has a violet gelatinous body of up to 200 mm in length, with eight pairs of dorsal appendages, lateral festooned edges and four rows of tube feet ventrally. Body wall ossicles comprise rods and crosses with three or four arms and a central bipartite apophysis borne on the primary cross; tentacles and gonad deposits comprise rods and crosses with three and four arms. This is the first report of a holothuroid from the Mar del Plata Canyon area.

Callocystites fresti sp. nov., and the significance of ambulacral branching in the Callocystitidae (Echinodermata, Glyptocystitoida)

Callocystites fresti sp. nov. is characterized by an elongate theca, protuberant periproct and raised ambulacral facets. Ambulacral branching in Callocystites is isotomous, but left‐ and right‐handed branches occur because the ambulacral groove branches in the same direction twice, interrupting the regularly alternating branching to brachioles. Branching in Strobilocystites does not interrupt the alternation of brachioles and lateral food grooves always pass adoral to the first brachiole of each branch. Sphaerocystites branched as in Strobilocystites. Other morphological features suggest Callocystites, Sphaerocystites and Strobilocystites are not closely related. Callocystites has open infra‐lateral and lateral circlets and five ambulacra; Sphaerocystites and Strobilocystites have closed/modified circlets and four ambulacra. In Callocystites and Sphaerocystites the B and D ambulacra differ from the others and they have one hydropore; in Strobilocystites all four ambulacra are the same and the hydropore is double. All three genera have large, globular thecae. Ambulacral branching was a response to increased food‐gathering requirements. The following are phylogenetically informative callocystitid characters: truly open vs closed/modified plate circlets; number of pectinirhombs; number of ambulacra; presence vs absence of the ‘B D different’ pattern of primary brachioles; single vs double hydropore.In echinoderms with five ambulacra in a 2–1–2 pattern ambulacral homologies are unambiguous: the single amb is A (III). In echinoderms without this pattern or with less than five ambulacra the hydropore or a single gonopore is best for orientation. Both always occur in the CD (V‐I) interambulacrum. The position of the periproct is unreliable. Different patterns and numbers of ambulacra in Palaeozoic echinoderms render a single developmental sequence improbable. Cystoids (blastozoans) had radial water vessels in their ambulacra and added new ambulacral plates terminally. Functional morphological considerations suggest tube feet were essential for food gathering. Copyright © 2014 John Wiley &amp; Sons, Ltd.

High opsin diversity in a non-visual infaunal brittle star.

BackgroundIn metazoans, opsins are photosensitive proteins involved in both vision and non-visual photoreception. Echinoderms have no well-defined eyes but several opsin genes were found in the purple sea urchin (Strongylocentrotus purpuratus) genome. Molecular data are lacking for other echinoderm classes although many species are known to be light sensitive.ResultsIn this study focused on the European brittle star Amphiura filiformis, we first highlighted a blue-green light sensitivity using a behavioural approach. We then identified 13 new putative opsin genes against eight bona fide opsin genes in the genome of S. purpuratus. Six opsins were included in the rhabdomeric opsin group (r-opsins). In addition, one putative ciliary opsin (c-opsin), showing high similarity with the c-opsin of S. purpuratus (Sp-opsin 1), one Go opsin similar to Sp-opsins 3.1 and 3.2, two basal-branch opsins similar to Sp-opsins 2 and 5, and two neuropsins similar to Sp-opsin 8, were identified. Finally, two sequences from one putative RGR opsin similar to Sp-opsin 7 were also detected. Adult arm transcriptome analysis pinpointed opsin mRNAs corresponding to one r-opsin, one neuropsin and the homologue of Sp-opsin 2. Opsin phylogeny was determined by maximum likelihood and Bayesian analyses. Using antibodies designed against c- and r-opsins from S. purpuratus, we detected putative photoreceptor cells mainly in spines and tube feet of A. filiformis, respectively. The r-opsin expression pattern is similar to the one reported in S. purpuratus with cells labelled at the tip and at the base of the tube feet. In addition, r-opsin positive cells were also identified in the radial nerve of the arm. C-opsins positive cells, expressed in pedicellariae, spines, tube feet and epidermis in S. purpuratus were observed at the level of the spine stroma in the brittle star.ConclusionLight perception in A. filiformis seems to be mediated by opsins (c- and r-) in, at least, spines, tube feet and in the radial nerve cord. Other non-visual opsin types could participate to the light perception process indicating a complex expression pattern of opsins in this infaunal brittle star.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1035) contains supplementary material, which is available to authorized users.

A detailed staging scheme for late larval development in Strongylocentrotus purpuratus focused on readily-visible juvenile structures within the rudiment.

BackgroundThe purple sea urchin, Strongylocentrotus purpuratus, has long been the focus of developmental and ecological studies, and its recently-sequenced genome has spawned a diversity of functional genomics approaches. S. purpuratus has an indirect developmental mode with a pluteus larva that transforms after 1–3 months in the plankton into a juvenile urchin. Compared to insects and frogs, mechanisms underlying the correspondingly dramatic metamorphosis in sea urchins remain poorly understood. In order to take advantage of modern techniques to further our understanding of juvenile morphogenesis, organ formation, metamorphosis and the evolution of the pentameral sea urchin body plan, it is critical to assess developmental progression and rate during the late larval phase. This requires a staging scheme that describes developmental landmarks that can quickly and consistently be used to identify the stage of individual living larvae, and can be tracked during the final two weeks of larval development, as the juvenile is forming.ResultsNotable structures that are easily observable in developing urchin larvae are the developing spines, test and tube feet within the juvenile rudiment that constitute much of the oral portion of the adult body plan. Here we present a detailed staging scheme of rudiment development in the purple urchin using soft structures of the rudiment and the primordia of these juvenile skeletal elements. We provide evidence that this scheme is robust and applicable across a range of temperature and feeding regimes.ConclusionsOur proposed staging scheme provides both a useful method to study late larval development in the purple urchin, and a framework for developing similar staging schemes across echinoderms. Such efforts will have a high impact on evolutionary developmental studies and larval ecology, and facilitate research on this important deuterostome group.

Phenoloxidase from the sea cucumber Apostichopus japonicus: cDNA cloning, expression and substrate specificity analysis

Phenoloxidase (PO) is a crucial component of the immune system of echinoderms. In the present study, the full-length cDNA of PO (AjPO) was cloned from coelomocytes of the sea cucumber Apostichopus japonicus using 3′- and 5′-rapid amplification of cDNA ends (RACE) PCR method, which is 2508 bp, with an open reading frame (ORF) of 2040 bp encoding 679 amino acids. AjPO contains a transmembrane domain, and three Cu-oxidase domains with copper binding centers formed by 10 histidines, one cysteine and one methionine respectively. Phylogenetic analysis revealed that AjPO was clustered with laccase-type POs of invertebrates. Using the isolated membrane proteins as crude AjPO, the enzyme could catalyze the substrates catechol, L-3,4-dihydroxyphenylalanine (l-DOPA), dopamine and hydroquinone, but failed to oxidize tyrosine. The results described above collectively proved that AjPO was a membrane-binding laccase-type PO. The quantitative real-time PCR (qRT-PCR) analysis revealed that AjPO mRNA was expressed in muscle, body wall, coelomocytes, tube feet, respiratory tree and intestine with the highest expression level in coelomocytes. AjPO could be significantly induced by lipopolysaccharide (LPS), peptidoglycan (PGN), Zymosan A and polyinosinic-polycytidylic acid (PolyI:C), suggesting AjPO is closely involved in the defense against the infection of bacteria, fungi and double-stranded RNA viruses.

Board 531 - Technology Innovations Abstract A Better Training Manikin for Intubating Neonates with Pierre Robin Sequence (Submission #298)

Introduction/Background Pierre Robin Sequence is an uncommon congenital condition characterized by a triad of glossoptosis, micrognathia and frequently, a U shaped cleft palate. These patients are prone to respiratory insufficiency due to upper airway obstruction and occasionally require intubation to support the airway or facilitate surgical procedures such as tongue-lip adhesion or mandibular distraction. Anesthetic implications are considerable for infants with Pierre Robin Sequence. Direct laryngoscopy and tracheal intubation can sometimes be extremely difficult causing an elevated rate of airway complications. The “TruCorp AirSim Pierre Robin” head is the only Pierre Robin Sequence intubation trainer available, and proved not to be difficult to intubate even for inexperienced providers. We recognized certain pitfalls of the Pierre Robin task trainer; the airway could be easily secured using conventional intubation techniques, and the task trainer head needed a body which could simulate controlled respiration’s with corresponding chest movement in order to add realism to the simulator. We set out to design a Pierre Robin Sequence manikin which could be used for education and training. Methods We attached a “TruCorp AirSim Pierre Robin” head to the body of a “Laerdal Resusci Baby” using Loctite heavy duty epoxy. In order to remotely simulate respirations, 15 feet of oxygen tubing was connected to a bag valve mask via a 3.5 mm endotracheal tube connector at the proximal end with the distal end connected to the tracheal main stem. Chest rise was created by gluing a SimMan bladder to the internal chest piece which then connected to the trachea. To meet the criteria for creating a difficult intubation using both direct and video laryngoscopy techniques, adaptions were made to the Pierre Robin head. The key components in designing such an airway was to limit the thyromental distance thereby restricting the alignment of oral and pharyngeal axis and decreasing the anterior mandibular space; the space in which the soft tissues of pharynx need to be displaced to visualize the vocal cords. To accomplish these goals, an 8 inch cable tie was used to capture the mandible to a channel in the baby’s head which housed the trachea to limit its movement. Results: Conclusion The resulting manikin exhibited external facial features similar to true patients with Pierre Robin Sequence. We also discovered that, as with to some infants with micrognathia, mask ventilation was challenging but ventilation through an LMA was possible. Direct and the Glidescope laryngoscopy demonstrated a Cormack-Lehane grade IV view. Securing the airway using a flexible fiberoptic bronchoscope alone was impossible, but the manikin could be successfully intubated via Glidescope-assisted fiberoptic intubation. Intubating a patient with complex airway anatomy, such as the anatomy of infants with Pierre Robin Sequence, can be quite challenging without proper practice. The ability to construct a realistic manikin presented its own difficulties, and required collaboration with experts from the simulation center who understood the mechanics, limitations and functions of a patient simulator, and the pediatric anesthesiologists who were familiar with the underlying anatomy and pathophysiology of the airway anatomy. The simulator generated is extremely realistic, and can be used to safely train difficult airway management to providers in the fields of Anesthesiology, Critical Care Medicine, Emergency Medicine and Otolaryngology; who may only occasionally encounter such patients in their practice.

Structural analysis of the starfish SALMFamide neuropeptides S1 and S2: The N-terminal region of S2 facilitates self-association

The neuropeptides S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide), which share sequence similarity, were discovered in the starfish Asterias rubens and are prototypical members of the SALMFamide family of neuropeptides in echinoderms. SALMFamide neuropeptides act as muscle relaxants and both S1 and S2 cause relaxation of cardiac stomach and tube foot preparations in vitro but S2 is an order of magnitude more potent than S1. Here we investigated a structural basis for this difference in potency using spectroscopic techniques. Circular dichroism spectroscopy showed that S1 does not have a defined structure in aqueous solution and this was supported by 2D nuclear magnetic resonance experiments. In contrast, we found that S2 has a well-defined conformation in aqueous solution. However, the conformation of S2 was concentration dependent, with increasing concentration inducing a transition from an unstructured to a structured conformation. Interestingly, this property of S2 was not observed in an N-terminally truncated analogue of S2 (short S2 or SS2; SFNSGLTFamide). Collectively, the data obtained indicate that the N-terminal region of S2 facilitates peptide self-association at high concentrations, which may have relevance to the biosynthesis and/or bioactivity of S2 in vivo.

Crown-of-thorns starfish

Crown-of-thorns starfish

The Role of Models in Science: A Multicomprehensive Experience with the Sea Urchin Paracentrotus Lividus

Model organisms are frequently used in science teaching as they provide good exemplars for students that want to understand basic biological phenomena. The common sea urchin Paracentrotus lividus is a familiar animal that students can frequently observe in nature and represents a good didactic model for teaching various biological concepts in schools. Its simple body structure and anatomy allow easily recognition of the main external and internal organs, including spines, tube feet, feeding apparatus (Aristotle's lantern), digestive tract and reproductive organs, providing several practical cues for interactive discussions on animal physiology and ecology. Additionally, this organism is an optimal model for in vitro observation of major reproductive processes, including release of gametes, fertilization and recognition of various embryonic stages. In fact, this species produces millions of spermatozoa and thousands of large, transparent eggs which can be easily collected; these can be used for in vitro fertilization and observation of basic biological processes such as mitosis, cell migration and differentiation and of early developmental stages.

Diel patterns of covering behavior by male and female Strongylocentrotus intermedius

Covering behavior refers to echinoids using their tube feet and spines to move objects, such as shells, stones, and algae fragments, onto their dorsal surface. Little information is available on the diel pattern of covering behavior in sea urchins. Here, we studied diel rhythms of covering behavior in male and female Strongylocentrotus intermedius in the laboratory. Both sexes of S. intermedius showed significant patterns in their diel covering behavior. Both the number of sea urchins covered (p = 0.012) and the number of shells used for covering (p = 0.006) show a significant rhythm. Sex, as a factor, did not show significant difference of covering behavior (p > 0.05). However, one-way repeated measured ANOVA showed that the interaction between diel cycle and sex had significant differences in both the number of sea urchins covered (p = 0.043) and the number of shells used for covering (p = 0.026). This indicates that the diel pattern of covering behavior was significantly different between males and females. Pearson correction analysis revealed that intensity of light was significantly correlated with both the number of sea urchins covered (R2 = 0.669, p < 0.001) and the number of shells used for covering (R2 = 0.672, p < 0.001) in males but not in females.

Trachythyoneflaccida, a new sea cucumber species from southern Angola (Echinodermata:Holothuroidea:Dendrochirotida:Cucumariidae) with key to the genus.

A new species of a cucumariid holothuroid, Trachythyone flaccida, is described from shallow water off the southern coast of Angola. This increases to 20 the number of species in the genus Trachythyone. The new species is characterized by a soft, barrel-shaped body, scattered non-retractile tube feet, and body wall ossicles comprising a superficial layer of cup-like baskets and a deeper layer of simple, smooth, multilocular plates; cross-shaped deposits may also occur. The new species appears most closely related to the subantarctic T. bouvatensis (Ludwig & Heding, 1935) and to the Brazilian T. crassipeda Cherbonnier, 1965. A key is provided to all species currently classified in this genus.

Effects of CO2-induced ocean acidification on physiological and mechanical properties of the starfish Asterias rubens

The increase in atmospheric CO2 due to anthropogenic activity results in an acidification of the surface waters of the oceans. Its impact will depend on the considered organisms and ecosystems. The intertidal may harbor organisms pre-adapted to the upcoming changes as they face tidal pH and temperature fluctuations. However, these environments will be more affected as shallow waters will face the highest decrease in seawater pH. In this context, the effects of reduced environmental pH on the physiology and tube feet mechanical properties of the intertidal starfish Asterias rubens, a top predator, were investigated during 15 and 27days. A. rubens showed a respiratory acidosis with its coelomic fluid pH always lower than that of seawater. This acidosis was most pronounced at pH7.4. Notwithstanding, the starfish showed no significant variations in RNA/DNA ratio of different tissues and in tube feet strength. However, respiration rates were significantly lower for individuals maintained at reduced seawater pH. Within the ocean acidification context, the present results suggest that A. rubens withstands the effects of reduced seawater pH, at least for medium term exposures.

Site Selectivity of the Pit Oichnus excavatus Donovan and Jagt Infesting Hemipneustes striatoradiatus (Leske) (Echinoidea) in the Type Maastrichtian (Upper Cretaceous, The Netherlands)

Two tests of the holasteroid echinoid Hemipneustes striatoradiatus (Leske) from the type area of the Maastrichtian Stage (Upper Cretaceous) bear a varied infestation of episkeletozoans (oysters, bryozoan colony, and serpulids), borings (probable Caulostrepsis isp., Oichnus simplex Bromley), surface abrasion (Gnathichnus? isp.), and pits (O. excavatus Donovan and Jagt). Only O. excavatus represents a premortem infestation. In one specimen, the four individual pits of this ichnospecies are each associated with a different ambulacrum and pore pairs that, in life, bore respiratory tube feet; the anterior ambulacrum, of different gross morphology, is not infested. In the second test, three out of four of the same ambulacra are infested, although there are also O. excavatus in the interambulacra. The association between O. excavatus and the ambulacra of the echinoid, and thus its tube feet, is open to several plausible explanations, but most likely provided some form of feeding or protective advantage to the pit-forming organism.

Penilidia desbarresi sp. nov. (Echinodermata: Holothuroidea: Elasipodida) from the upper slope of Newfoundland and re-description of P. ludwigi (von Marenzeller, 1893)

Penilpidia desbarresi sp. nov. was collected in the Desbarres Canyon at a depth of 525 m, off the southeastern coast of insular Newfoundland, eastern Canada. The new species differs from the type species Penilpidia ludwigi (von Marenzeller, 1983) in having larger middle spines on arched rod-type ossicles on the dorsum and by having the lobe around the posterior body end formed by six pairs of very small tube feet. Penilpidia desbarresi sp. nov was photographed in situ and sampled on a single occasion in July 2007. This gonochoric species (~1–2 cm long) was found on a muddy substrate and individuals were aggregated, reaching a density of ~50 ind. m−2 . Preliminary evidence points to brooding, which would be a first for the family Elpidiidae. Penilpidia ludwigi, not recorded for more than 100 years after its first description, is re-described.

Tube foot preservation in the Devonian crinoid Codiacrinus from the Lower Devonian Hunsrück Slate, Germany

Fossilized tube feet are described on Codiacrinus schultzei Follmann from the Lower Devonian Hunsruck Slate of Germany. This is the first definitive proof of tube feet on any fossil crinoid. Three lightly pyritized, flattened tube feet are preserved in a single interray of this cladid crinoid. The tube feet were at least 7 mm long. Their preservation is very similar to the tube feet reported previously from a Hunsruck ophiuroid, except that the Codiacrinus tube feet have small papillae, similar to living crinoids.

Expression of amino acid transporter genes in developmental stages and adult tissues of Antarctic echinoderms

Epithelial cells in the body wall of adult and developmental stages of marine invertebrates absorb dissolved organic material directly from seawater. Despite over a century of study, little is known about the molecular biological mechanisms responsible for this transport process. Previous studies on embryonic and larval Antarctic echinoderms show that amino acid uptake could provide an important supplement of metabolic substrates. In the present study, partial cDNA sequences of 11 putative amino acid transporter genes were isolated from six species of Antarctic echinoderms including the Antarctic sea stars Acodontaster hodgsoni, Diplasterias brucei, Odontaster meridionalis, Odontaster validus, and Perknaster fuscus, and the Antarctic sea urchin Sterechinus neumayeri. Conserved domains of cDNA-deduced amino acid sequences characterized these genes as being members of a family of amino acid transporters (solute carrier family 6). Expression of these genes was detected throughout embryonic and larval development of two species that have contrasting developmental modes (A. hodgsoni: lecithotrophic; O. meridionalis: planktotrophic). In all six species studied, the expression of amino acid transporter genes was detected in tube feet and digestive organs of adult animals, demonstrating that members of a single amino acid transporter gene family are expressed during the entire life history of a marine invertebrate. The identification of these genes is an important step toward developing a mechanistic understanding of amino acid transport capacities in Antarctic marine invertebrates.

C-opsin Expressing Photoreceptors in Echinoderms

Today's progress in molecular analysis and, in particular, the increased availability of genome sequences have enabled us to investigate photoreceptor cells (PRCs) in organisms that were formerly inaccessible to experimental manipulation. Our studies of marine non-chordate deuterostomes thus aim to bridge a gap of knowledge regarding the evolution of deuterostome PRCs prior to the emergence of vertebrates' eyes. In this contribution, we will show evidence for expression of a c-opsin photopigment, which, according to our phylogenetic analysis, is closely related to an assemblage of chordate visual c-opsins. An antibody raised against sea urchins' c-opsin protein (Sp-Opsin1) recognizes epitopes in a variety of tissues of different echinoderms. While in sea urchins this c-opsin is expressed in locomotory and buccal tube feet, spines, pedicellaria, and epidermis, in brittlestars and starfish we found the immuno-reaction to be located exclusively in cells within the animals' spines. Structural characteristics of these c-opsin+ PRC types include the close vicinity/connection to nerve strands and a, so far unexplored, conspicuous association with the animals' calcite skeleton, which previously has been hypothesized to play a role in echinoderm photobiology. These features are discussed within the context of the evolution of photoreceptors in echinoderms and in deuterostomes generally.

ON A NEW GENUS AND TWO NEW SPECIES OF PROSOBRANCHIA (MOLLUSCA), PARASITIC ON THE TROPICAL SEA URCHIN ECHINOMETRA MATHAEI

ABSTRACT Males and females of the parasitic prosobranch Monogamus entopodia n. gen., n. sp. occur together within the same tube foot of Echinometra mathaei in the Gulf of Elat (= Gulf of 'Aqaba), Red Sea. The anatomy of the parasite and its relation to the host have been studied, and observations on its biology are given. The snout has a most unusual shape and is deeply inserted into the tube foot, but does not penetrate the hydro-vascular system, the tube foot component of which degenerates as a result of parasitization. Males and females of another species, Monogamus interspinea n. sp., described from a few Pacific Ocean localities, live close together on the aboral side of the test of Echinometra mathaei. Monogamus is probably related to Robillardia Smith, which lives in the rectum of Echinometra.

Light perception in brittle stars: detection of the molecular actors

Event Abstract Back to Event Light perception in brittle stars: detection of the molecular actors Jerome Delroisse1*, Jérôme Mallefet2 and Patrick Flammang1 1 University of Mons, Marine Biology Organisms & Biomimetics, Belgium 2 University of Louvain-La-Neuve, Marine Biology, Belgium Echinoderm photoreception is usually considered as enigmatic because of the lack of eyes in most of the species. Although a diffuse dermal and/or neural light sense has been described in some echinoderms (1), in sea urchins and sea stars photoreceptor cells expressing opsins are localized in specialized organs: the tube feet and the optic cushions on the arm tip, respectively (2,3,4). However, opsins are also expressed in the aboral integument of sea urchins and sea stars, indicating that light perception is certainly a multi-component process (5). Numerous brittle stars are described as light sensitive (6) though almost nothing is known about photoreception in the class Ophiuroidea. Lens-like arm plates were identified in Ophiocoma wendtii and, together with the underlying photoreceptors, could constitute a new type of compound eye (7,8). In the European brittle star Amphiura filiformis, light perception is unequivocal and allows the animal to adapt its feeding activity to the day/night cycle (9,10). This species could also use photoreceptors to perceive its own bioluminescence. Light perception at the level of bioluminescent organs has already been described for a cephalopod (11) and a ctenophore (12) and could also occur in brittle stars. Transcriptome profiling in A. filiformis indicate the expression of both opsins and cryptochrome. If cryptochromes are considered as components of the circadian clock that control daily rhythms (13), opsins are the main actors of vision in metazoans (14). A. filiformis is characterized by the expression of two opsin mRNAs, which were mainly detected in regenerating arms. Phylogenetic analysis revealed one Go-opsin and one R-opsin. The retinol metabolism pathway needed for the synthesis of the opsin light sensitive chromophore was also retrieved in the transcriptome. Finally, several drosophila-like and mammalian-like phototransduction actors were identified in arm tissues, confirming the implication of an opsin-based system. These opsins are probably involved in ambient light perception and also, possibly, in bioluminescence perception. A cryptochrome-mediated process could secondarily complete the role of the opsins or at least be linked to the day/night rhythm perception.