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lineata. The ratios of Types A∶B∶C involved in prey killing and ingestion were 1∶2.5∶5 and 1∶2∶3, respectively. These findings support the CSCC hypothesis. They also indicate that Type Cs predominate in killing small, hard-surfaced, motile, crustaceous prey. Chemoreceptor-bearing Type Bs and Type As assist in prey killing and assume somewhat greater roles in ingestion. Thus, CSCC types differ with respect to their afferent sensory roles as well as their subsequent efferent roles in killing and ingestion. We conclude that CSCC types perform overlapping and complementary roles during feeding.AbstractWhile so-called brown bodies were first defined in the 1950s as colorful aggregates of cells in the general cavity of echinoderms and other marine benthic taxa, their distribution and role have not yet been fully clarified. This work characterized free coelomocytes and corresponding aggregates ("bodies") in the hydrovascular system and perivisceral coelom, as well as those attached on the membranes of the viscera, in the holothuroid Cucumaria frondosa. Responses to the presence of foreign particles were investigated, providing novel insights on the immune system. A total of eight coelomocyte cell types was detected, while aggregates were formed of three to six types of coelomocytes. Only red-colored aggregates were found in the hydrovascular system, whereas brown aggregates were confined to the perivisceral coelom. The encapsulation mechanism of foreign particles injected in the hydrovascular system was monitored. Particles were first gathered by phagocytes and vibratile, crystal, and morula cells into a whitish aggregate that was then covered by hemocytes, imparting a red color to the aggregates. After their transfer to the perivisceral coelom, aggregates became brown and were ultimately expelled through the anus. Finally, a range of stressors (i.e., harvesting method, presence of a predator, and physical injury) was found to increase the abundance of aggregates, thus highlighting the role of these bodies in the immune response of C. frondosa.AbstractSpatiotemporal environmental change can produce phenotypic differences within and between populations. For scyphozoans, the effect of environmental variation on phenotype has been unclear because of multiple challenges, including difficulties delimiting populations. Marine lakes, bodies of seawater entirely surrounded by land, provide an opportunity to study discrete populations and capture responses to perturbations. We use this opportunity to compare Mastigias papua (Lesson, 1830) medusae before and after a demographic and environmental perturbation. We reconstructed mitochondrial DNA haplotype networks, measured morphological variation, and assessed swimming behavior of pre- and post-perturbation samples to evaluate two hypotheses about the source of variation recolonization from an alternate location or endemic phenotypic variation. We found significant differences between samples in morphology (F &gt; 9.5, P 0.001). We could not distinguish the source of endemic variation; this will require genomic or experimental analyses. Increasing climatic variability emphasizes the need for understanding population-level responses to environmental change and how responses may be modified by sources of intraspecific variation.AbstractSymbiotic dinoflagellates in the family Symbiodiniaceae release mobile compounds (e.g., glucose, glycerol, amino acids, and lipids) to their host's tissues. Little is known about how different symbionts affect quantitative and qualitative differences in these compounds. We tested how symbiont identity affects glycerol and glucose pools in the tissues of the sea anemone Exaiptasia pallida ("Aiptasia"). We infected symbiont-free anemones with three different symbiotic dinoflagellates Breviolum minutum isolated from our Aiptasia stock, B. minutum isolated from a different Aiptasia population, and the free-living Effrenium voratum. We measured free glycerol and glucose levels in host tissues under photosynthetic conditions, as well as metabolite release by these algae when freshly isolated from Aiptasia and incubated in a host tissue homogenate. Anemone tissues containing the stock B. minutum accumulated glycerol at a higher symbiont cell-specific rate than those containing the alternative B. minutum or Elishment in the cnidarian-dinoflagellate partnership.AbstractThe Pacific white shrimp, Litopenaeus vannamei, is important as the principal species in the worldwide aquaculture of shrimp. It has also become a model in the study of crustacean biology, especially because it is one of the first decapod crustaceans to have its genome sequenced. This study examined an aspect of the sensory biology of this shrimp that is important in its aquaculture, by describing its peripheral chemical sensors and how they are used in acquiring and consuming food pellets. [https://www.selleckchem.com/ selleck products] We used scanning electron microscopy to describe the diversity of sensilla on the shrimp's major chemosensory organs antennules, antennae, mouthparts, and legs. Using behavioral studies on animals with selective sensory ablations, we then explored the roles that these chemosensory organs play in the shrimp's search for, and acquisition and ingestion of, food pellets. We found that the antennules mediate odor-activated searching for pellets, with both the lateral and medial antennular flagella contributing to this behavior and thus demonstrating that both aesthetasc (olfactory) and distributed chemosensors on the antennules can mediate this behavior. Once the shrimp finds and grasps the food pellet, the antennular chemoreceptors no longer play a role, and then the chemoreceptors on the mouthparts and legs control ingestion of the pellets. This sequence of chemosensory control of feeding in L. vannamei, a dendrobranchiate crustacean with small antennules and an ability to live and feed in both benthic and pelagic environments, is generally similar to that of the better-studied, large-antennuled, benthic reptantian crustaceans, including spiny lobsters (Achelata), clawed lobsters and crayfish (Astacidea), and crabs (Meirua).