The toxicity of biomolecules obtained from sea anemones in vitro does not necessarily justify their function as toxins in the physiology of the anemone. That is why anatomical and physiological considerations must be taken into account in order to define their physiological role in the organism. In this work, antibodies generated to Sticholysin II, a cytolysin produced by the Caribbean Sea anemone Stichodactyla helianthus, are used as specific markers to explore the sites of production and storage of the cytolysin in the sea anemone. The immunoperoxidase staining developed gave specific dark-brown staining in tentacles and mesenteric filaments as well as in basitrichous nematocysts isolated from tentacles of S. helianthus. These results support the role of these proteins as toxins in the physiology of the anemone, especially in functions such as in predation, defense and digestion.

The application of DNA barcoding represents a complementary and efficient approach to identifying specimens at all stages of their life cycle when used in combination with traditional morphological methods. Due to difficulties obtaining samples from the deep sea (> 200 m), these methods have been less frequently applied to deep-water taxa. We used DNA-barcoding techniques to enhance large-scale biodiversity initiatives for deep-pelagic crustaceans within the Gulf of Mexico, a region that has recently been identified as one of the world’s four most hyperdiverse ocean ecosystems. This study was conceptualized in direct response to the Deepwater Horizon Oil Spill in 2010, which identified major knowledge gaps in our understanding of deep-sea biodiversity. We employed traditional Sanger sequencing and a genomic skimming approach to target the mitochondrial ribosomal large subunit 16S and the protein-coding cytochrome oxidase subunit 1 (COI). Alongside these molecular approaches, traditional taxonomic investigations allowed for advancements in biodiversity, evolutionary relationships, cryptic species complexes, and distributional records across four abundant and common deep-pelagic orders (Amphipoda, Euphausiacea, Lophogastrida, and Decapoda). DNA barcodes were successfully obtained from 82 species for a total of 158 and 169 new 16S and COI sequences, respectively. Evidence of cryptic diversity has been found in the genera EucopiaDana, 1852 (Lophogastrida) and Allosergestes Judkins & Kensley, 2008 (Decapoda). New records for the Gulf of Mexico of species of LanceolaSay, 1818 (Amphipoda), Eupasiphae Wood-Mason in Wood-Mason & Alcock, 1893, PasiphaeaSavigny, 1816, and MeningodoraSmith, 1882 (Caridea) are presented. Preliminary results allow us to reconsider the current classification and evolutionary relationships of several lineages. The urgency to document biodiversity in the deep-pelagic is pressing against a backdrop of future threats including oil spills and deep-sea drilling.

The influence of two bivalve diets (Mytilus chilensis "chorito" and Tagelus dombeii "navajuela") at three temperatures (13, 15, and 18°C) was studied during the reproductive conditioning of Chorus giganteus (Lesson, 1829). Energy budgets were determined taking into account energy acquisition (ingestion and absorption) and energy expenditure (oxygen consumption, ammonia production, and energy placed into mucus production and egg laying). Relative physiological condition was assessed by calculating the scope for growth index (SFG). Diet and temperature both played key roles in the physiological energetic and reproductive conditioning of this snail. Tagelus was the preferred prey, probably because of its greater vulnerability to predatory attack by C. giganteus. The highest feeding rate was observed at 15°C, coinciding with optimal growth. Absorption efficiency was similar with *Author for correspondence.

Hidrozoos de aguas poco profundas fueron recolectados en 17 estaciones, en julio del 2004. Las estaciones se localizaron en manglares, pastos marinos y arrecifes coralinos. Se encontraron hidrozoos de dos subclases (Anthoathecata y Leptothecata), 11 familias, 27 géneros y 34 especies. Se indican la localidad de recolecta, la profundidad, el tipo de sustrato, la descripción y las figuras de 15 especies de hidrozoos tecados. Se confirma la presencia de Hebellopsis communis Calder, 1991a y Antennella siliquosa (Hincks, 1877) para el Mar Caribe. Se expresa la abundancia relativa en tres categorías: abundante, común y rara. Las especies más abundantes fueron Dynamena crisioides Lamouroux, 1824 en el hábitat de manglar, Cnydoscyphus marginatus (Allman, 1877) y Sertularella diaphana (Allman, 1885) en los arrecifes. Monostaechas quadridens (McCrady, 1859) y Diphasia tropica Nutting, 1904 fueron de baja representación en las muestras. Los sustratos más colonizados fueron la raíz sumergida de mangle rojo y las esponjas en arrecife. El hidrozoo más colonizado fue C. marginatus. El material fue depositado en la colección de invertebrados marinos del Acuario Nacional de Cuba.ABSTRACT Hydrozoans from shallow waters were collected at 17 stations in July 2004. Stations were located in mangrove forests, seagrass meadows and coral reefs. Two subclases (Anthoathecata and Leptothecata) of hydrozoans were found, including 11 families, 27 genera and 34 species. The collection site, depth, type of substrate, description and pictures are recorded for the fifteenth thecate hydrozoan species. The presence of Hebellopsis communis Calder, 1991a and Antennella siliquos (Hincks, 1877) is confirmed for the Caribbean Sea. The relative abundance is expressed in three categories: abundant, common and rare. Most abundant species were Dynamena crisioides Lamouroux, 1824 in mangrove habitat, Cnydoscyphus marginatus (Allman, 1877) and Sertularella diaphana (Allman, 1885) in coral reefs. Monostaechas quadridens (McCrady, 1859) and Diphasia tropica Nutting, 1904 were rare in general. The most colonized substrates were the submerged red mangrove roots and sponges in the reef. The most colonized hydrozoan was C. marginatus. Specimens were deposited in the collection of marine invertebrates at the National Aquarium of Cuba.

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