Capitate Tentacles Research Articles

First record of Cnidocodon leopoldi Bouillon, 1978 (Cnidaria: Anthoathecata) in the Atlantic Ocean

Specimens of the hydromedusa Cnidocodon leopoldi Bouillon, 1978 were collected in waters off the northeast Brazilian coast between 7.4°S, 34.3°W and 8.7°S, 34.8°W. The genus can be distinguished from other anthomedusae by the presence of four marginal perradial bulbs having an adaxial nematocyst cushion and branched capitate tentacles, an umbrella with scattered nematocysts, and gonads around a cylindrical manubrium shorter than the umbrella. Specimens were assigned to C. leopoldi due the tentacles with 4-5 branches and the absence of ocelli on tentacle bulbs differing from the congeneric Cnidocodon ocellata Huang, Xu, Lin & Qiu, 2008. This study represents the first record of the species in the Atlantic Ocean.

Erratum to: A New Deep-Sea Suctorian-Nematode Epibiosis (Loricophrya-Tricoma) from the Blanes Submarine Canyon (NW Mediterranean).

During a pluri-disciplinary study carried out within the frame of the Spanish research project DOS MARES, multicore samples were collected along the Blanes submarine canyon and its adjacent open slope to study the structure and dynamics of the meiofaunal organisms, mainly nematodes. Among the 5808 nematode individuals identified, only 190 of them belonged to the genus Tricoma (Desmoscolecidae), and only two harboured epibiont suctorian ciliates. The three specimens were located near the tail of the basibionts. A careful examination of the ciliates revealed that they were suctorians, which are here described as a new species of Loricophrya, namely L. mediterranea sp. nov. The new species is characterized by having a conical, slightly elongated lorica, narrowing towards posterior end; an anterior end inward curved, surrounding the lorica opening; a body placed near the lorica opening, occupying 1/3 of the lorica length, 4–8 capitate tentacles, and a peripheral, oval to sausage-shaped macronucleus. Our findings represent the first known report of an association with a deep-sea species of Tricoma, and the first record in the Mediterranean Sea, for a species of Loricophrya. The significance of the relationships between suctorian ciliates and their host in extreme environments such as deep-sea submarine canyons is discussed.

A New Deep-Sea Suctorian-Nematode Epibiosis (Loricophrya-Tricoma) from the Blanes Submarine Canyon (NW Mediterranean).

During a pluri-disciplinary study carried out within the frame of the Spanish research project DOS MARES, multicore samples were collected along the Blanes submarine canyon and its adjacent open slope to study the structure and dynamics of the meiofaunal organisms, mainly nematodes. Among the 5808 nematode individuals identified, only 190 of them belonged to the genus Tricoma (Desmoscolecidae), and only two harboured epibiont suctorian ciliates. The three specimens were located near the tail of the basibionts. A careful examination of the ciliates revealed that they were suctorians, which are here described as a new species of Loricophrya, namely L. mediterranea sp. nov. The new species is characterized by having a conical, slightly elongated lorica, narrowing towards posterior end; an anterior end inward curved, surrounding the lorica opening; a body placed near the lorica opening, occupying 1/3 of the lorica length, 4-8 capitate tentacles, and a peripheral, oval to sausage-shaped macronucleus. Our findings represent the first known report of an association with a deep-sea species of Tricoma, and the first record in the Mediterranean Sea, for a species of Loricophrya. The significance of the relationships between suctorian ciliates and their host in extreme environments such as deep-sea submarine canyons is discussed.

Astrocoryne cabela, gen. nov. et sp. nov. (Hydrozoa : Sphaerocorynidae), a new sponge-associated hydrozoan

The family Sphaerocorynidae includes two valid genera and five species, most of which have a confusing taxonomic history. Here, a new genus and species, Astrocoryne cabela, gen. et sp. nov., is described from the Maldives and the Red Sea, based on both morphological and molecular evidence. Astrocoryne cabela has an apomorphy represented by the type of tentacles, here named ‘dicapitate’, and consisting of capitate tentacles with a proximal capitulum-like cluster of nematocysts. Molecular analyses confirmed the monophyly of this species, as well as its belonging to the Sphaerocorynidae, together with Sphaerocoryne spp. and Heterocoryne caribbensis Wedler & Larson, 1986, for which we present molecular data for the first time. Moreover, the high divergence of A. cabela from other species of the family justifies the establishment of a new genus. Interestingly, specimens from the Maldives and the Red Sea showed marked morphological variation in the polyp stage, although only a slight genetic divergence was detected. This study highlights that a comprehensive morpho-molecular assessment of Sphaerocorynidae is strongly needed in order to clarify the taxonomic issues and the diversity of this taxon.

Monodisc strobilation in Japanese giant box jellyfish Morbakka virulenta (Kishinouye, 1910): a strong implication of phylogenetic similarity between Cubozoa and Scyphozoa.

Both sexes of the Japanese giant box jellyfish Morbakka virulenta were collected from the Seto Inland Sea, western Japan in December 2011, in order to observe the developmental processes from polyps to medusae. The medusa production in M. virulenta is up to now a unique process in cubozoans in that it exhibits a form of monodisc strobilation where the polyp is regenerated before the medusa detaches. This mode of medusa production was previously thought to be exclusive to scyphozoans. The general shape of young medusae resembles that of other cubozoans such as Alatina moseri and Copula sivickisi, but is differentiated from these by the short capitate tentacles and the lack of gastric filaments in the stomach. The unique medusa production of M. virulenta highly implies a phylogenetic similarity between cubozoans and scyphozoans.

Chemosensory pathways in the capitate tentacles of the hydroid Cladonema

The introduction of an extract of Artemia into the sea water bathing tentacles from the hydroid Cladonema triggers a burst of electrical activity that can be recorded intracellularly from cnidocytes in the capitate tentacles. These bursts, which are composed of a variety of events, including action potentials and EPSPs, are Ca2+ dependent, and are abolished by pretreatment with NiCl2, suggesting that voltage-gated Ca2+ channels are involved in their generation or transmission. Intracellular injection of Lucifer Yellow and recordings from pairs of cnidocytes reveal that the cnidocytes are electrically coupled to one another, but that they are not uncoupled by heptanol. The role of these chemosensory pathways in priming the cnidocytes for discharge is discussed.

Presence of two new species of suctorian (Protozoa: Ciliophora) epibiont on the marine crustacean isopod Excirolana chiltoni

Specimens of the marine isopod Excirolana chiltoni collected in Hokkaido (northern Japan) showed epibiont protozoan ciliates belonging to two species of loricate suctorian: Acineta hokkaidensis sp. nov. and Acineta excirolensis sp. nov. Acineta hokkaidensis is larger, with an elongated body covered by a lorica. The short stalk had 15–18 longitudinal striations. The contractile vacuole was located apically. The macronucleus was posterior. Two fascicles of capitate tentacles located at the edges of the apical area project through the anterior aperture of the lorica. The suctorians were found on the pereiopods and antennae of the isopod. Acineta excirolensis which is smaller and triangular in shape, showed a very wide lorica and a noticeably long stalk. At the edges of the apical region there were two lobulate actinophores, each with a fascicle of capitate tentacles. The contractile vacuole was anterior and spherical, and the macronucleus was central. These suctorians were attached as planobionts on the pereiopods of the isopod. The taxonomic position of both species was analysed in relation to other similar species previously described.

The hydroid and medusa of <i>Sarsia bella</i> sp. nov. (Hydrozoa, Anthoathecatae, Corynidae), with a correction of the life cycle of <i>Polyorchis penicillatus</i> (Eschscholtz)

A new hydrozoan, Sarsia bella sp. nov. is described in both its hydroid and medusa stage from north of Puget Sound, Washington in the San Juan Islands, USA and off the southernmost tip of Vancouver Island, Canada. The medusa is distinguished from other Sarsia species by 16 exumbrellar nematocyst patches and in being more transparent or glass like when living than any other known species of the genus. The exumbrellar nematocyst patches become indistinct in mature specimens and in those crowded in culture, with single nematocysts increasingly spaced out. The hydroid, both field-collected and raised in culture from its medusa, forms small, upright stolonal colonies not more than 1.5 mm high. The hydranths bear an oral whorl of four to five capitate tentacles, and immediately below a second whorl of slightly shorter capitate tentacles. In thriving colonies there is occasionally a whorl of small filiform tentacles on the lower part of the hydranth. Medusa buds develop in the middle of hydranth below the capitate tentacles and above the reduced filiform tentacles, if present. Young medusae are liberated with the typical 16 exumbrellar nematocyst patches. The hydroid of this species was originally mistaken for the hydroid of Polyorchis penicillatus . Brinckmann-Voss (1977) reported a small corynid hydroid living on the margin of rock scallop shells. Medusae liberated from this hydroid were at that time believed to be those of Polyorchis penicillatus (Eschscholtz) present in the plankton. Immature medusae of these two species appear strikingly similar, especially with regard to their exumbrellar nematocyst patches, four tentacles and abaxial ocelli. Since then however, this connection has been proven wrong, because an identical hydroid was raised from the medusae of the new species Sarsia bella . Second generation medusae raised in the laboratory were carefully compared with medusae liberated from field collected hydroids (thought to have been Polyorchis penicillatus ), and these were found to be identical with meduse of Sarsia bella. Young medusae of P. penicillatus from the plankton can be clearly distinguished from S. bella medusae by the number of their exumbrellar nematocyst patches. Both P. penicillatus and Sarsia bella have eight adradial rows of exumbrellar nematocyst patches when young, however each row in P. penicillatus consists of at least three vertically alligned patches whereas each row never has more than two patches in S. bella . In both species the patches consist of microbasic p-mastigophores, but capsules in the case of P. penicillatus are larger than those in S. bella . Later stages of the two species are easily distinguished using other morphological characters with only four tentacles in S. bella and more than four in P. penicillatus . No hydroid of the genus Polyorchis has been described to date.

The life cycle of <i>Halimedusa typus</i>, with discussion of other species closely related to the family Halimedusidae (Hydrozoa, Capitata, Anthomedusae)

The little-known Anthomedusa Halimedusa typus has been collected from several locations in California, Oregon, and British Columbia on the Pacific coast of the United States. The adult medusa is redescribed based on new observations of living material and is found to have capitate tentacles. Polyps of H. typus were raised several times after spawning field-collected medusae in the laboratory; the cultures on one occasion lived for more than a year. The capitate polyp is solitary and very tiny, emerging from a basal perisarc measuring 200-300 µm in diameter. One cultured polyp produced a medusa, which is described. The taxonomic positions of several other morphologically-similar Anthomedusae in the Capitata are compared and discussed here. Tiaricodon coeruleus and Urashimea globosa are moved from the Polyorchidae to the Halimedusidae, and the similarity of Boeromedusa auricogonia (Boeromedusidae) to all of these medusae and to the genera Polyorchis, Scrippsia and Spirocodon of the family Polyorchidae is considered. The group of species under consideration is basically restricted to the Pacific Ocean, except for T. coeruleus and U. globosa, which have also been collected in the south Atlantic and south Atlantic/Antarctic. It is noted that medusae of the Halimedusidae are typically found quiescent near the surface, whereas those of the Polyorchidae either rest on the bottom or must continue pulsating to stay up in the water column, indicating a basic underlying difference in buoyancy and resultant behavior between the medusae in these two families.

Observations on the White sea hydroid,Sarsia producta(Wright, 1858) (Hydrozoa: Athecata)

Abstract Polyps of the White Sea hydroid Sarsia producta were collected, described and figured, in order to gain new insight into its ecology, morphology, colonial structure, and behaviour. Specific modes offeeding behaviour were observed on hydro ids in situ, and their diet was examined. The diet of Sarsia producta is diverse and based on a wide range of items from different systems: dead organic matter, settled on the substrate or suspended in the water, phytoplankton and zooplankton, and epibenthic animals and algae. Successful capture of such a variety of food items is achieved by the particular feeding movements of the flexible body, well co-ordinated with the movements of hypos tome and capitate tentacles. In total, these movements create a complicated feeding behaviour unusual among hydroids.

Mechanoelectric transduction in nematocytes of a hydropolyp (Corynidae)

In sensitivity and ultrastructure of their cnidocil apparatus (CA), the nematocytes (stinging cells) of hydrozoans are analogous to hair cells of vertebrates and epidermal mechanoreceptors of insects. Intracellular recordings using current and voltage clamp in the capitate tentacles of the marine hydropolyp Stauridiosarsia producta (Corynidae) now revealed that depolarizing receptor potentials and receptor currents are generated in nematocytes (stenotele type) in response to mechanical stimulation of the CA. The responsive cells were identified by injection of Lucifer Yellow. For recording, the tentacles were isolated from the polyp and held by a suction capillary. Stimuli were applied by a glass probe moved electromagnetically or piezoelectrically.

Occurrence and Distribution of RFamide-Positive Neurons Within the Polyps of Coryne sp. (Hydrozoa, Corynidae).

The neuronal network of the hydrozoan polyp Coryne sp. contains RFamide-positive neurons. Within the body column, these neurons are centralized in a basal ring and a distal field of ganglionic cells surrounding the peristome. The capitate tentacles are traversed by thick RFamide-positive neurites. Their pericarya are centralized in the knobby heads of the tentacles, forming a brightly fluorescing plaque after immunolabeling with an antibody against the RFamide sequence. Numerous dendrite-like extensions project from these cells towards the cell bodies of the nematocytes. The possible role of these dendrites in communication between adjacent nematocytes is discussed.

A Cytological Study and Reclassification of Trichophrya collini (Saedeleer & Tellier)1

ABSTRACT. Trichophrya collini has a polygonal, dorsoventrally flattened body (up to 75 μm diam.), with capitate tentacles arranged in 1–3 rows within peripheral fascicles. There is a central polymorphic macronucleus, an associated micronucleus, and numerous peripheral contractile vacuoles with ventral discharge pores. The cell has a multilayered cortex and the cytoplasm contains suctorian organelles such as crescentic bodies, elongate dense bodies, and haptocysts. The highly contractile tentacles have an axoneme with an outer ring of 24 microtubules separated into six groups and an inner ring of six curved lamellae, each with five microtubules. The lamellae at the distal and proximal ends of the axoneme are arranged in a helix, and the outer ring microtubules are joined in a distal connective sheath. In the apical knob of the tentacle, the haptocysts are borne on a central capsule, Reproduction is by endogenous budding to produce a single oval‐shaped swarmer, with equatorial ciliature, which metamorphoses within 3 h. These observations suggest that this organism, previously known as Heliophrya collini Saedeleer & Tellier, is synonymous with Platophrya rotunda Gönnert, Craspedophrya rotunda Rieder, and Heliophrya rotunda Matthes. Its endogenous mode of budding assigns it to the genus Trichophrya. but it is distinct from Trichophrya rotunda Hentschel, and should be reclassified to Trichophrya collini (Saedeleer & Tellier).

INHIBITION OF NEMATOCYST DISCHARGE DURING FEEDING IN THE COLONIAL HYDROIDHALOCORDYLE DISTICHA(=PENNARIA TIARELLA): THE ROLE OF PREVIOUS PREY-KILLING

The colonial hydroid Halocordyle disticha (= Pennaria tiarella) kills prey with stenotele nematocysts. These nematocysts become less responsive after heavy feeding, but their killing activity is restored after hydranths are placed in fresh medium. Nematocysts of unfed hydranths became inactive when neighboring hydranths (either attached or separated) were fed; the effect increased with the amount of previous prey-killing. The loss of nematocyst activity was not due to stenotele depletion or compounds in prey fluids; waste products produced by the hydroid or prey had little effect. Extracts of capitate tentacles produced inactivation, and stenoteles were completely inhibited in a concentrated solution of stenotele discharge products. Our results indicate that the inactivation of stenoteles is due to the accumulation of materials released from the stenoteles during discharge.

The cellular basis of the aggressive acrorhagial response of sea anemones.

Some sea anemones possess structures called acrorhagi at the base of the tentacles. The acrorhagi are utilized solely for aggression. Acrorhagial aggression involves very exquisite intra- and interspecific recognition. This study examined acrorhagi and putative acrorhagial analogues or homologues in four species of sea anemone. The morphology and ultrastructure of tentacles, pseudoacrorhagi, column vesicles, and verrucae (adhesive column vesicles) differed from that of acrorhagi. Coral capitate tentacles and acrorhagi have different surface morphology, nematocysts, and functions. Besed on morphology, acrorhagi seem more likely to be homologous to tentacles than to verrucae. Acrorhagial nematocyst discharge and ectodermal peeling, the culmination of the response, were shown to require prior acrorhagial expansion in Anthopleura krebsi and Bunodosoma cavernata. A mechanical mechanism is suggested where- by distention of the acrorhagus opens a ciliary pit on the nematocyte surface and exposes the pit wall and microvilli, which may contain the chemoreceptors for the peeling process, including nematocyst discharge. A similar system may also be responsible for changing the threshold of nematocyst discharge in sea anemone tentacles. A case of possible neurosecretion in an anthozoan was also shown in this study.

The Medusa of Velella velella (Linnaeus, 1758) (Hydrozoa, Chondrophorae)

A mature medusa of Velella velella (Linnaeus, 1758) is reported for the first time from the North Atlantic; previously adult medusae were known only from the Mediterranean. This specimen, collected by SCUBA divers, is the largest specimen recorded to date. Distinctive features are: two opposite adaxial-axial pairs of perradial capitate tentacles; two marginal bulbs lacking tentacles; conical manubrium with 4 perradial longitudinal gonads; perradial exumbrellar cnidae tracts; cnidome of stenoteles and macrobasic euryteles; and zooxanthellae within the subumbrella. Since this specimen was collected near the surface and has zooxanthellae, it is likely that V. velella medusae are epipelagic.

Polyp and medusa of Dipurena bicircella n. sp. (Hydrozoa: Corynidae) from Northern California

The polyp and medusa of Dipurena bicircella n. sp., a metagenic hydrozoan from Northern California, USA, is described. The arrangement of capitate tentacles of the polyp, in two alternating cycles or circlets, is unique to the genus Dipurena as well as to the family Corynidae. Medusae released in the laboratory attained sexual maturity in 2 weeks. The adult medusa can be distinguished from other medusae of the genus by means of 2 gonad rings, a slight terminal nematocyst cluster on each tentacle, and a relatively small size (about 2 mm in bell height). The polyp was not found in association with sponges, as is the case with some of the other polyps of the genus Dipurena. The medusa is not yet known from the plankton.

HYDROID AND YOUNG MEDUSA STAGES OFDIPURENA STRANGULATA(HYDROZOA, CORYNIDAE)

The hydroid stage in the life history of Dipurena strangulata, a relatively well-known medusa along the United States east coast, is described for the first time. A previous description of the young medusa does not accord with observations recorded here, but is similar to and may have been based on young Linvillea agassizi rather than D. strangulata. Of the described hydroids of Dipurena, D. strangulata is most like D. reesi morphologically, but differs in the position of the filiform tentacles and the number of endodermal cells in the capitate tentacles. The status of the various species of Dipurena described from the North American Atlantic coast is reviewed.

The feeding biology of the gymnoblastic hydroid, Pennaria tiarella

AbstractThe role in food capture of the nematocysts on the filiform and capitate tentacles of Pennaria tiarella is discussed. The feeding response of Pennaria tiarella to Artemia extracts consists of cone bending and mouth opening. A similar feeding response has been demonstrated to be induced by proline at concentration as low as 10−6M. Pipecolic acid, a proline analog, also elicits a feeding response. Proline causes the head of the capitate tentacles to shrink, thereby causing the cnidocils of the large stenoteles to be prominent.

THE MORPHOLOGY AND DEVELOPMENT OF ACAULIS ILONAE SP. N. (ORDER ANTHOMEDUSAE/ATHECATAE, FAM. ACAULIDAE)

A new species of athecate hydroid of the genus Acaulis Stimpson 1854 (Acaulidae) is described. The species is named Acaulis ilonae sp. n. It is characterised by having short capitate tentacles in young specimens, while in adult specimens the tentacles become progressively longer towards the aboral region. Gonophores are born in the axils of the tentacles. The development of the embryo, the structure of the adult hydroids, and their asexual and sexual reproduction are described.