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Aquatic Invertebrates

Acacia Alcivar-Warren, Kelly Bateman, Morag Clinton, Leo Foyle, Gregory Lewbart, Richmond Loh, and Julius Tepper

Porifera (sponges)

Coelenterates:

• Cnidarians (Hydrozoa, Scyphozoa/jellyfish, Anthozoa/anemones and corals)
• Mollusca
  • Bivalves (oysters, clams, mussels, scallops, cockles)
  • Cephalopod (Nautiloidea, Coleiodea; Decapodiformes/cuttlefish and squid, Octopodiformes/octopus)

  Gastropods:

  • Prosobranchia (limpets, abalone, cowries, conch, winkles, snails, whelks)
  • Opistobranchia (sea hares, sea slugs)
  • Pulmonata (snails)
• Crustaceans:
  • Shrimp
  • Lobsters
  • Crabs
  • Crayfish
• Echinoderms:
  • Crinoidea (crinoids, sea lilies, feather stars)
  • Asteroidea (sea stars/starfish)
  • Ophiuroidea (brittle stars, basket stars)
  • Echinoidea (sea urchins, sand dollars)
  • Holothuroidea (sea cucumbers)
  • Concentrocycloidea
• Urochordates:
  • Ascidians (sea squirts)
  • Thalaceans (salps, doliolids)
  • Larvacians

Porifera (Sponges)

Overview

The phylum Porifera is a diverse group of ancient and anatomically undifferentiated animals commonly referred to as sponges. Until the middle of the 18th century, sponges were classified as plants (Ruppert et al., 2004). Sponges occur in the fossil record back to the Precambrian era (over 600 million years ago) and were the most important contributors to reefs during the Paleozoic and Mesozoic eras (Hooper and Van Soest, 2002). All members lack defined organs, with differentiated connective tissue cells performing necessary biologic functions. A unique system of water canals facilitates transport of food, gametes, and waste products. Nearly all species are sessile, and most are marine. Of the approximately 8300 species belonging to over 680 genera, only about 3% occur in freshwater (Hooper and Van Soest, 2002; Ruppert et al., 2004). Sponges are normally found on firm substrates in shallow water, although some occur on soft bottoms, or at great depth.

Despite their being termed "primitive" or "simple" in form and function, Srivastava et al. (2010) discovered that at least one species shares over 70% of its DNA with humans. This finding may lead to further use of sponges in biomedical research, where they are already making important contributions in the areas of embryology, pharmacology, and toxicology. Sponges are highly sensitive to water quality and flow changes, including suspended sediments. Zinc and copper may be toxic to some species. Infectious diseases are not well characterized. Bacterial and algal microbiota, and occasionally protozoa have been implicated.

Clinical Signs

• Sudden death - toxicity, trauma, extreme sedimentation.
• Poor growth - water pollution, sedimentation, inadequate food supply, loss of symbiotic bacteria.

A listing of outbreaks of the major disease syndromes of sponges is given in Table 1.1. A list of the etiology of the major disease syndromes of sponges can be found in Appendix 1.1.

Coelenterates

Taxonomic Overview

This large phylum is made up of the cnidarians, including scyphozoans (jellyfishes), anthozoans (stony corals, soft corals, sea anemones) and hydrozoans (hydras, fire coral, Portuguese Man-o-War) and the ctenophores (comb jellies). This is an economically important group for research, environmental monitoring, public and private display, and tourism. Jellyfish exhibits are now some of the most popular displays in public aquariums and upscale restaurants throughout the world. Coral reefs collectively are one of the most beautiful, diverse, and fragile ecosystems on the planet. Investigations on the diseases of corals are some of the most active areas of research for any aquatic animal group.

Key Points

• Some diseases of hard and soft corals have been well documented, but etiologies are often an enigma. The nomenclature for many of the infectious diseases is in the process of standardization.

  Table 1.1 Miscellaneous disease outbreaks in invertebrates - Porifera (sponges).

  Outbreak Species Ecological description Microbiological description Indian Ocean, 1884 Ircinia Unknown Fungal filaments destroy sponge body leaving a crust of spongin fibers Florida, 1895 Commercials Loss of commercial sponges Internal tissue completely eroded Tunisia, 1906 Hippospongia equina Attributed to shallow water and low water exchange Dermal cortex covered in white, gray or green liquid Caribbean, 1938 Hippospongia Heavy mortality Fungi always present Florida Keys, 1939 Commercials 70-95% mortality Unidentified fungal filaments in diseased tissue Cuba, 1939 Commercials 70-95% mortality Unidentified fungal filaments in diseased tissue British Honduras, 1939 Commercials Unseasonably high temperature and salinity Unbranched fungal filaments between live and dead tissue Panama, 1984-1995 Iotrochota, Amphimedon compressa, Aplysina fulva, Callyspongia vaginalis, Niphates, Xestospongia, Verongula rigida, Ircinia Disease symptoms evident over multiple census periods. Cross species contact infections unsuccessful. Excision of diseased tissue often successful as a treatment Spreading lesions. I. birotulata: dulling of surface tissue, tissue loss and white discoloration. A. compressa: glossing of surface and advancing narrow brown band. Ap. fulva: glossing of surface tissue and a narrow brown band progression, exposure of skeletal fibers Belize, 1985 Geodia papyracea Mutualism changed to disease in high water temperature Extensive tissue decay caused by proliferation of cyanobacterial symbiont Mediterranean, 1986-1990 Hippospongia, Spongia Devastated commercial sponge populations and more prevalent in shallow, warm water. Spread rapidly Rapidly spreading white spots, brittle skeletons, putrefied tissue, white veil (Oscillatoria?). Unidentified bacteria tunnel through skeleton Sicily and Ligurian coast, 1986-1995 Spongia and Hippospongia spp., Petrosia ficiformis, Ircinia variabilis, Anchinoe paupertas Disappearance of Spongia officinalis in Marsala Lagoon; 60% of commercial specimens affected in 1987, 5% in 1988 and 20% in 1989. Recolonization by 1995 White patches observed on the surface of affected sponges. Ovoid bacteria filled the canaliculi of exposed skeletal fibers Libya, 1987 Commercial Pollution, environmental conditions, and neglect of fishery Unknown North Wales, 1988-1989 Haliclona oculate, Halichondria panicea A number of individuals affected in 1988-1989 but no disease detected since Brown decaying patches in H. oculata (possibly algal overgrowth) and decayed patches in H. panicea covered in white bacterial film Mediterranean, 1994-1996 Ircinia spinosula, Ircinia Massive mortality in 1994 Decay of spongin fibers No excavation of spongin fibers. Putative agent unknown Belize, 1996 Xestospongia muta No data Not performed Great Britain, 1998 Rhopaloeides odorabile Soft and fragile tissue with portions of pinacoderm eroded away to reveal the skeletal fibers Bacteria observed burrowing through the spongin fibers. Causative agent identified as an alpha-proteobacterium Mediterranean, 1994-1996? Ircinia spinosula, Ircinia Massive mortality in 1994 Decay of spongin fibers No excavation of spongin fibers. Putative agent unknown Papua New Guinea, 1996-2000 Ianthella basta. Diseased specimens of Jaspis and Xestospongia Decline in health and abundance of I. basta. Brown lesions with rotted tissue, large holes and brown biofilm Five bacterial strains within the Bacillus and Pseudomonas genera were strongly correlated with disease Curacao, 2000 Xestospongia muta White holes with brittle dead tissue around perimeter of lesions Not performed Greece, 2001 Aplysina aerophoba Massive...