Types Of Cnidae Research Articles

Revealing hidden diversity among upside-down jellyfishes (Cnidaria: Scyphozoa: Rhizostomeae:

Morphological variability within Cassiopea is well documented and has led to inaccuracies in the establishment of species boundaries in this taxon. Cassiopea medusae specimens from the Western Pacific (Japan and the Philippines) were analysed using multiple lines of complementary evidence, including types of cnidae, macro-morphology and molecular data. These observations lead to the recognition of two distinct species: Cassiopea mayeri, sp. nov. and a previously synonymised variety now raised to species level (Cassiopea culionensis, stat. nov.). These species can be distinguished from each other using morphological features. Herein, sexually dimorphic traits are included for the first time in the descriptions of Cassiopea species. Nematocyst types not previously observed in the genus are also reported. Molecular analyses, based on individual and combined markers (16S + cytochrome c oxidase I, COI), also support two distinct species; they are not sister taxa, and both are nested together within a clade of other Cassiopea members from the Australian and Indo-Pacific regions. Species richness is underestimated in the Western Pacific region, and integrative approaches are helpful to reveal and describe species. The systematics of Cassiopea is far from completely understood, but the present study represents an important further step. http://www.zoobank.org/References/B1A66787-009D-4465-954A-412C6878FCB4.

Cnida sequestration in aeolid nudibranchs: variability and retention time of sequestered cnidae in the opalescent sea slug, Hermissenda crassicornis (Gastropoda, Nudibranchia)

Aeolid sea slugs can isolate and store stinging cnidae obtained from their cnidarian prey, presumably for their own defence. There are 30 different varieties of cnidae, identified by their unique structure. The aeolids engulf the cnidae and store them in a functional state at the tips of their cerata. Although the process of cnida sequestration is reasonably well understood in aeolids, two critical questions remain: (1) are cnida types uniformly distributed among the cerata and (2) how long do sequestered cnidae persist? I collected opalescent sea slugs (Hermissenda crassicornis (Eschscholtz, 1831)) from Barkley Sound, British Columbia, Canada, and determined the cnida complements in four cerata per individual by microscope. The cnida complements differed between cerata from different body regions within the individual (values of Whittaker’s dissimilarity index from 2.5% to 36.3%). Furthermore, the cnidae varieties in low abundances are not consistently present within an individual. I also found that H. crassicornis fed a non-cnidarian diet lost cnidae over time, but the cnidarian-fed individuals did not: 3 of 10 H. crassicornis on the non-cnidarian diet lacked cnidae completely at 42 days. Future studies of cnida sequestration should be mindful that one ceras does not give an adequate representation of the distribution of sequestered cnidae.

Sea anemones (Cnidaria, Actiniaria) of Singapore: redescription and taxonomy of Phymanthuspinnulatus Martens in Klunzinger, 1877.

Despite the ubiquity of sea anemones (Cnidaria: Actiniaria) in tropical ecosystems, our understanding of their biodiversity and taxonomy is limited. Here we re-establish the identity of an intertidal zooxanthellate species, Phymanthuspinnulatus Martens in Klunzinger, 1877. Originally described from a single preserved specimen in the Berlin Museum by CB Klunzinger, his brief footnote lacked crucial details to positively identify the species. Our redescription is based on more than 50 living individuals of P.pinnulatus collected from its type locality, Singapore. These were examined and compared with type materials of the species and its congeners. Specimens of P.pinnulatus differ from syntypes of species described as Phymanthuslevis Kwietniewski, 1898 from Indonesia, as well as Phymanthussansibaricus Carlgren, 1900 and Phymanthusstrandesi Carlgren, 1900, both described from East Africa. Phymanthuspinnulatus was encountered on the lower intertidal, among coral rubble and between rocky crevices. It is vibrantly coloured and has 96 marginal tentacles with branching outgrowths along each, resulting in a ‘frilly’ appearance. The anemone has a flat expanded oral disc, with discal tentacles that are inconspicuous and reduced, unlike syntypes of its congeners. Details of its live appearance, musculature, and cnidom are also provided for the first time. Overall, types of cnidae and capsule sizes differ from other known species of Phymanthus documented elsewhere. It is inferred that P.pinnulatus has a wide distribution that extends eastwards from Singapore, as far as Ambon and the Torres Straits. Some individuals reported as Phymanthusmuscosus Haddon and Shackleton, 1893 and Phymanthusbuitendijki Pax, 1924 are probably P.pinnulatus. This morphological analysis provides new insights into the characters used to delimit P.pinnulatus, clarifies its geographical distribution, and contributes to an ongoing revision of the genus Phymanthus.

First inventory of sea anemones (Cnidaria: Actiniaria) from La Paz Bay, southern Gulf of California (Mexico).

Sea anemones from the Mexican Pacific are poorly known. We report and redescribe eight species of sea anemones from La Paz Bay in the southern Gulf of California, Mexico. As a result of this inventory, we validate records for 30 species from the Mexican Pacific, 23 of them from the Gulf of California and 15 of those present in La Paz Bay. We provide taxonomic diagnoses, images of internal and external anatomy, size ranges and types of cnidae, and geographic and bathymetric distribution, and discuss the taxonomic diagnostic characters for each species. This study is the first illustrated inventory of sea anemones from La Paz Bay.

The effects of symbiotic state and nutrient availability on the cnidom in the model sea anemone, Exaiptasia diaphana

The symbiotic relationship between corals and zooxanthellae allows coral reefs to thrive. The symbiont translocates nutrients which it derives from photosynthesis to the coral, which then uses the nutrients for its growth, reproduction, metabolism, and the maintenance of structural integrity. The majority of the coral’s nutritional input is lost when the coral loses its symbionts in a bleaching event. However, the importance of the symbiotic state to the cnidom of corals remains unknown. The facultative symbiotic anemone Exaiptasia diaphana, common name Aiptasia, is widely used as a model organism to understand the symbiotic relationship between coral and their symbionts. We experimentally rendered Aiptasia aposymbiotic using a menthol treatment. We exposed symbiotic anemones and aposymbiotic anemones to differing feeding regimes to investigate the impact of nutritional input on the cnidom. Symbiotic state and feeding regime significantly affected the: ratio of cnida types in tentacles; the mean volume of cnidae; and the mean density of cnidae in Aiptasia. When Aiptasia becomes aposymbiotic, its tentacles possess more spirocysts and fewer penetrant-type nematocysts. Furthermore, cnidae in aposymbiotic anemones tended to be smaller than in symbiotic anemones. In addition, the ratio of cnida types and the mean volume of cnidae were significantly affected by nutrient availability in aposymbiotic anemones. When nutrients were exogenously supplied, the cnidom of aposymbiotic anemones became comparable to that of symbiotic anemones. Moreover, the mean size of cnidae significantly increased. Thus, the cnidom is a dynamic entity that is significantly influenced by the symbiotic state of the anemone and/or the availability of nutrients.

Description of the Sea Anemone <i>Anthopleura Thallia</i> (Gosse 1854)

The inconspicuous intertidal sea anemone Anthopleura thallia is redescribed based on recent collections in England and Ireland. The redescription includes a complete account of the types and sizes of cnidae, and documents variability in colouration and pattern within and among populations. This is the first record of the species in Ireland. Anthopleura thallia is sympatric with the better-known and widespread species Aulactinia verrucosa, and the two may co-occur at a single site; they differ in colouration, reproductive biology, internal anatomy and the types of cnidae in the body. Marymegan Daly (Corresponding author: daly.66@ osu.edu), Department of Evolution, Ecology & Organismal Biology, The Ohio State University, 1315 Kinnear Rd, Columbus, OH 43212, USA; Bernard Picton, Zoology Department, Ulster Museum, Belfast, Northern

Structural diversity, systematics, and evolution of cnidae

Cnidae are secreted by the Golgi apparatus of all cnidarians and only cnidarians. Of the three categories of cnidae (also called cnidocysts), nematocysts occur in all cnidarians, and are the means by which cnidarians defend themselves and obtain prey; spirocysts and ptychocysts are restricted to a minority of major taxa. A cnida discharges by eversion of its tubule; venom may be associated with the tubule of a nematocyst. About 30 major morphological types of nematocysts are recognized, but no single nomenclature for them is accepted. Function seems not to correlate tightly with morphology—nematocysts of at least some types are used both offensively and defensively. Similarly, it is not clear if morphology correlates with toxicity. Some types of nematocysts are taxonomically diagnostic whereas others are widespread. Nonetheless, an inventory of types of cnidae (the cnidom), with their distribution and size, is an essential component of most taxonomic descriptions. Complicating the taxonomic value of cnidae are the facts that not all members of a species may have the same types of cnidae, even at the same life-cycle stage, and size of nematocysts of a species may vary geographically and with size of individual. The diversity of nematocysts is so great and the features within each major type are so variable that homologies have not been determined. Nematocyst complement, morphology, and size likely reflect both phylogeny and biology; the feedback between the two may confound analysis. Although cnidae are valuable in taxonomy of at least some groups, more understanding of the forces that affect them is needed for their systematic and phylogenetic value to be understood and their potential as indicators of evolution to be realized.

Composition, biometry and statistical relationships between the cnidom and body size in the sea anemone Oulactis muscosa (Cnidaria: Actiniaria)

This study analyses the possible relationships between body size and length of cnidae from different tissues of the sea anemone Oulactis muscosa. We describe the cnidom, providing new qualitative and quantitative data. Our description adds spirocysts for tentacles and acrorhagi, and is more precise about the ranges and types of basitrichs, microbasic b-mastigophores, and holotrichs. We distinguish two types of holotrichs in the acrorhagi, and differentiate between microbasic b-mastigophores and basitrichs in the actinopharynx and mesenterial filaments. A relationship between cnida length and body weight was not demonstrated. The results are based on a complete account of cnida types from all tissues, and considering the great number of capsules measured (5400) and the modern statistical tools employed, we think that a normal distribution of cnida lengths is uncommon, perhaps refuted. This finding is very important when a quantitative analysis of cnidae is necessary and an adequate statistical tool must be used. We have shown that generalized linear models are an alternative and therefore analyses can be done with parametric methods despite the non-normal distribution of cnida size. The use of these statistical tools should be generalized since appropriate package for analyses (like the R package) are available from the web and the obtained results are robust and powerful.

Use of cnidae in taxonomy: implications from a study of Acrozoanthus australiae (Hexacorallia, Zoanthidea)

Cnidae have been used in hexacoral taxonomy since 1900 but their value at species-level remains controversial. Data given in descriptions have generally been cnida types, their distribution, and capsule sizes presented as ranges (maxima and minima). More recently, measurements of cnida capsules, treated as populations, have been employed. Sampling cnidae extracted from zooids ranging from buds to full-grown polyps, we have analysed 28 300 random measurements of capsule length and width in 133 samples taken from two colonies of the zoanthid Acrozoanthus australiae, one from Queensland, Australia, and one from Indonesia. Using image analysis we measured large holotrichs, microbasic b-mastigophores and p-mastigophores, basitrichs being absent. Length has a lower coefficient of variation than width. Up to 12% of sample distributions were non-normal, depending on the test employed, but there was no consistent pattern of departure from normality. Sample sizes of 50 are regarded as adequate for the calculation of means and variances but need to be larger (contrary to current practice) for an accurate estimation of range. Moreover, some ranges were asymmetrical with respect to the sample mean. Statistical methods for comparing ranges are lacking, so sample size, mean and a measure of variance must always be included. Capsule sizes often differed significantly along the length of tentacles and filaments; they also showed significant differences between polyps within a colony, sometimes clearly correlated with polyp size. It is suggested (based on size frequency distributions that are right skewed or bimodal) that new buds may contain residual cnidae derived from the parent polyp as well as others that have differentiated in situ. Though length appears to be the most useful capsule descriptor, bivariate (width: length) scattergrams provide a concise summary of capsule size, also displaying cnida type and source. We make several recommendations for future practice.

Anatomy and Taxonomy of Three Species of Sea Anemones (Cnidaria: Anthozoa: Actiniidae) from the Gulf of California, Including Isoaulactinia hespervolita Daly, n. sp.

Specimens of actiniarians from the Gulf of California having a column densely covered with vesicles or verrucae have been attributed to one of three species: Anthopleura dowii, Bunodactis mexicana, or Bunodosoma californica. These three species are difficult to distinguish and are at least partly synonymous: Bunodosoma californica is a pro parte synonym of A. dowii and Bunodactis mexicana is a junior synonym of A. dowii. However, based on anatomy, coloration patterns, types of cnidae in the column, and habitat preferences, I discern three distinct species. I describe specimens attributed to Bunodactis mexicana not belonging to A. dowii as Isoaulactinia hespervolita, n. sp. I redescribe Bunodosoma californica and A. dowii and designate a lectotype for Bunodosoma californica to resolve taxonomic confusion.

Changes of cnida composition during planula development of a reef-building coral Acropora nasuta

Changes of cnida composition during larval development are described for a scleractinian coral Acropora nasuta. Two types of cnidae, a microbasic b-mastigophore nematocyst and a spirocyst, were observed in planulae; whereas, four types were identified in polyps: microbasic p-mastigophore, holotrichous isorhiza, and the two types of cnidae found in planulae. The cnidae of planulae appeared 3-4 days after fertilization and gradually increased in number until the 8th day. The appearance of cnidae 3-4 days after fertilization and the maximum number of cnidae on the 8th day after fertilization coincided with the period of first settlement and maximum settlement, respectively. On the 15th day of in vitro culture, the number of nematocysts remained, but the spirocysts decreased until they were virtually absent in the larvae. The spirocysts might be used up during the repeated trial of settlement. We supposed that the nematocysts act as a defense against predators, whereas the spirocysts were used for initial attachment to the substrata. The number of cnidae will be a useful indicator to find larval maturity.

Collagenaceous, thiol-containing proteins of cnidarian nematocysts: A comparison of the chemistry and protein distribution patterns in two types of cnidae

1. 1. Nematocyst structural proteins (NSP) from the sea anemones Aiptasia pallida and Metridium senile and the siphonophore Physalia physalis are primarily low molecular weight collagens linked by disulfide bonds. 2. 2. NSP patterns resolved by SDS-PAGE revealed a common, major collagen species (40 kDa) in each nematocyst type, together with other collagens and non-thiol-containing proteins. 3. 3. For each cnidarian, NSP glycosylation profiles were significantly different. 4. 4. Monoclonal antibodies against Aiptasia NSP demonstrated a differential distribution between capsule wall and thread. 5. 5. NSP differences would account for the diversity of morphologic and functional types.

Use of electrical stimulation for discharging cnidom components of a species of Cerianthus (Anthozoa: Cnidaria)

Direct-current electrical stimulation was used as a means of discharging cnidom components from the marginal tentacles of a species of Cerianthus from Southern Queensland, Australia, in order to facilitate the study of cnidom components by light microscopy. The cnidom consists of b-rhabdoids (3 types), spirocysts, and ptychocysts. Threshold pulses of between 1 and 2 V with a frequency of 1 pulse per second for 2 sec discharge all types of cnidae. However, large numbers of certain cnida types discharge after a longer period of stimulation.