Eccentricity of the Apical System and Peristome of Sand Dollars (Echinodermata: Echinoidea: Clypeasteroida: Scutellina)

Eccentricity, location of structures away from a central position, is associated with directional movement. Although sand dollars have directional movement, only eccentricity of the anus is apparent. Eccentricity of the apical system and peristome is less apparent. We have found the apical system and the peristome are statistically significantly slightly anterior in Mellita tenuis, Mellita quinquiesperforata, Mellita isometra, and Encope aberrans. The apical system of Leodia sexiesperforata is central and that of Echinarachnius parma is anterior, whereas the peristome of both is statistically significantly slightly posterior. The usual selective pressure for pronounced anterior location of the mouth in animals with directional movement may be countered by the mode of feeding in sand dollars that utilizes the oral surface. The basis for the eccentricity of the apical system is not known

Nitrate Impacts on Florida Apple Snail (Pomacea paludosa) Survival and Growth

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A note on calculating P values from 0.15-0.005 for the Anderson-Darling normality test using the F distribution

Exact P values in the range 0.15-0.005 for the Anderson-Darling statistic can be calculated using the F distribution by modifying the asymptotic statistic A* with a simple formula. The formula calculates F* and P is calculated using [image omitted]�.EDF test,

Zoogeography and systematics of the shallow water echinodermata of Texas

Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references.Not availabl

Autotomy of Globiferous Pedicellariae in the Sea Urchin Lytechinus variegatus (Echinodermata: Echinoidea)

Pedicellariae are small structures on sea urchins used in cleaning the test and in defense. In most species, when globiferous pedicellariae (one of 4 types) contact an object it causes the pedicellariae to grasp the object in a defensive reaction. Very few instances have been documented where pedicellariae are released into the water column. Lytechinus variegatus was exposed to 4 treatments of control, physical tapping, water swirling around the animal, and direct jet of water at the animal in 4 separate experiments including two live field tests, an anesthetized test, and a euthanized test. Globiferous pedicellariae were released into the water in response to the direct jet of water, with the greatest response seen in individuals tested in the field and the least response in euthanized urchins. The other treatments did not elicit a large response. Release of pedicellariae into the water may be a preemptive defense before coming in physical contact with a predator

Amphilepididae Matsumoto 1915

Family Amphilepididae Matsumoto 1915 <p> Type genus. <i>Amphilepis</i> Ljungman 1867</p>Published as part of <i>Pomory, Christopher M., Carpenter, Jerry H. & Winter, John H., 2011, Amphicutis stygobita, a new genus and new species of brittle star (Echinodermata: Ophiuroidea: Ophiurida: Amphilepididae) found in Bernier Cave, an anchialine cave on San Salvador Island, Bahamas, pp. 50-68 in Zootaxa 3133</i> on page 53, DOI: <a href="http://zenodo.org/record/205286">10.5281/zenodo.205286</a&gt

Amphicutis Pomory, Carpenter & Winter, 2011, gen. nov.

<i>Amphicutis</i> gen. nov. <p> <b>Diagnosis.</b> Disk with imbricating scales on dorsal and ventral surface (Fig. 3). Radial shields oval, on disk edge, separated medially along their entire length by one column of disk scales. Second tentacle pore of oral frame outside mouth slit. Genital scales flat and thin, no bursal sacs. Ventral tooth at the apex of each jaw broadly rounded. Proximal oral papillae small rounded, in infradental position. Distal oral papillae oblong, closing off mouth slit with distal oral papilla on adjoining jaw. Small oral papilla sometimes present between infradental and distal papillae. Non-madreporite oral shields small ovals, similar in appearance to disk scales, madreporite distinct. Adoral shields narrow, curved, thin, not tightly fused to oral plates or oral shield. Translucent layer of skin raised above surface of arms in life, usually visible in preservation. Disk and arms often formed mainly by soft tissue outlining plates and scales, but lacking significant calcification.</p> <p> <b> Type Species. <i>Amphicutis stygobita</i> sp. nov.</b> </p> <p> <b>Etymology.</b> Name of the new genus is Latin, feminine derived from <i>amphi</i>, around, and <i>cutis</i>, skin.</p> <p> <b>Remarks.</b> The new genus is distinguished from <i>Amphilepis</i>, the only current genus in the family Amphilepididae, by the 1) oral shields (distinctly separate from disk scales, and triangular in shape with a broad distal edge in <i>Amphilepis</i>), 2) adoral shields-oral shield union (tightly fused and thicker than disk scales forming the more typical oral frame of ophiuroids in <i>Amphilepis</i>), 3) oral papillae (two papillae per side with the proximal papilla set more to the side than infradental in <i>Amphilepis</i>), 4) skin (lack of pronounced soft tissue in <i>Amphilepis</i>), and 5) ventral tooth (triangular in <i>Amphilepis</i>). See Mortensen (1927) and Mills and O’Hara (2010) for good illustrations of <i>Amphilepis</i>.</p>Published as part of <i>Pomory, Christopher M., Carpenter, Jerry H. & Winter, John H., 2011, Amphicutis stygobita, a new genus and new species of brittle star (Echinodermata: Ophiuroidea: Ophiurida: Amphilepididae) found in Bernier Cave, an anchialine cave on San Salvador Island, Bahamas, pp. 50-68 in Zootaxa 3133</i> on pages 53-54, DOI: <a href="http://zenodo.org/record/205286">10.5281/zenodo.205286</a&gt