Lecture Ctenophora (Comb Jellies) 1 Phylulm Ctenophora

Phylum Ctenophora The Comb jellies Resemble cnidarian medusas. Use cilia for locomotion.

Phylum Ctenophora (Comb Bearers) Defining Characteristics Plates of fused cilia arranged in rows for swimming Adhesive prey capturing cells (colloblasts) on tentacles Comb jellies are delicate, transparent, nonstinging predators Phylulm Ctenophora 3

Ctenophore Structure Body surface has two large tentacles and eight rows of comb-like paddles Comb paddle has thousands of cilia used to swim Their tentacles have the adhesive colloblasts to capture prey and they have a stomach, mouth, pharynx, and anal pores. They have a nerve network that is rather complex and an apical sense organ. All ctentophores are hermaphrodites and most reproduce sexually. They generally range in size from.6 cm to 30.5 cm. 4 Phylulm Ctenophora

Apical Sense Organ Apical sense organ located on the aboral surface controls beating of cilia Statolith and balancers 6 Phylulm Ctenophora

Colloblasts Colloblasts are a cell type found in ctenophores. They are widespread in the tentacles of these animals and are used to capture prey. Sticky retractile tentacle used to catch prey Colloblast discharge an adhesive thread which is sticky to the touch Some spp. lack tentacles and the body is studded (=scattered) with colloblasts 7 Phylulm Ctenophora

Colloblasts (Morphology) Colloblasts are microscopic, sticky structures used to adhere to the prey of a ctenophore. Usually the classes Cydippida and Lobata have colloblasts on their tentacles. After a prey is caught by a colloblast, the tentacle is contracted and the prey is brought by the predator s mouth. There the prey is released and ingested.

CHARACTERISTICS All ctenophores are bioluminescent, meaning they are capable of producing light. Bioluminescence is caused by the activation of calcium-activated proteins named photoproteins in cells called photocytes, which are often confined to the meridional canals that underlie the eight comb rows. Two types of chemicals involved in light production, called luciferin and luciferase, are bound together in a photoprotein. This molecule can be triggered to produce light when calcium is added to the system. Photoproteins emit flashes of very bright light for a fraction of a second

CHARACTERISTICS Ctenophores have two digestive openings, but rarely use the anus for defecation Bi-radial symmetry and three germ layers (epidermis, gastrodermis, mesoglea if included) Mesoglea holds muscle cells and amoebacytes All Ctenophores have a distinct larval form before adulthood

Ctenophore diversity Most species live in the open ocean and are not well studied New studies use submersibles and divers to collect specimens, eliminating specimen destruction by fast towed nets Phylum Ctenophora Order Cyphidds Order Lobata Order Beroida Phylulm Ctenophora 11

Order Cydippids (Morphology) Egg-shaped bodies (sea gooseberry) Order includes pleurobrachia Tentacles on opposite sides of body Body can be flattened to increase range of tentacles Tentacles have tentilla (small branched tentacles) with colloblasts Generally coil around prey to kill Combs are spaced evenly around the body

Lobata (Morphology) Order also called Lobates Have pair of muscular lobes extending from mouth (Darth Vader?) Two comb rows on each lobe and two on each side between lobes Some can clap combs to push water rapidly and move opposite

Lobata (Morphology) Auricle : ciliated ribbon-like projections Tentacles in grooves on lobes, have auricles between lobes and mouth Auricles have cilia to create current and flush prey into the mouth Generally prey on plankton

Order Beroida Order also known as Nuda No feeding appendages, but pharynxes have macrocilia Marcocilia are large bundles of cilia that work to bite off pieces of whatever is being consumed Prey on other ctenophores When not eating, a ridge shuts the mouth by connecting with the other part of the ridge Can consume prey substantially larger than itself 15 Phylulm Ctenophora

(A) Pleurobrachia bachei deploys a web of sticky tentacles to capture active prey. (B) Bathyctena chuni from the deep Pacific with its mouth. (C) Dryodora glandiformis, a polar species that specializes in larvaceans. (D) The lobate Ocyropsis maculata immaculata has no functional tentacles as an adult and uses its muscular lobes to capture prey directly. (E) The showercap ctenophore Thalassocalyce inconstans from the aboral end. In this species, the lobes are fused and there are no auricles. (F) The lobate Leucothea pulchra viewed along the body axis from the oral end; it is swimming straight toward the viewer. Note the sinuous auricles (au) (G) Beroe forskalii, having ingested a large portion of a Leucothea. The comb rows (arrowheads) and orange papillae of the prey can be seen inside

Digestion Feed on plankton, other ctenophores and other Cnidarian jellies Gut extends through the entire body; mouth is at the oral end Anal pore is at the aboral end The prey of cydippid and lobate ctenophores in general includes small crustaceans such as copepods, amphipods, and even euphausiids (krill), and larvae of other marine invertebrates such as clams and snails. the principal prey of beroid ctenophores is other ctenophores. In turn, ctenophores are eaten by many species of medusae (jellyfish) as well as by sea turtles and some fish. 17 Phylulm Ctenophora

Digestion Enzymes and contractions of pharynx li quidize prey Cilia move the resultant mush into the s tomach canal system Nutritive enzymes break down the mus h in the stomach Ciliary rosettes in canal transfer nutrient s to muscles in mesoglea Most waste is ejected through the mout h, rarely through the anal pores. Exact mode of excretion is unknown

Development (Embryology)

Remarkably distinct from other animal genomes in their content of neurogenic, immune and developmental genes. Nature 510, 109 114

Ecological impacts in the late 1980s the Western Atlantic ctenophore Mnemiopsis leidyi was accidentally introduced into the Black Sea and Sea of Azov via the ballast tanks of ships, Mnemiopsis can breed very rapidly and tolerate a wide range of water temperatures and salinities. The impact was increased by chronic overfishing, and by eutrophication

Changes in the Black Sea pelagic foodweb due to overfishing and Mnemiopsis introduction

https://www.youtube.com/watch?v=pimibtqjlzc&ebc=anypxkrstyqi QsHL7gTMWe_dROiDEG42HJDmBwC1KBgy1iXtSZCl- K0VuBTaPEPOPp577s3ydq54HpeJO8UrDlTJdycBBy4VeQ http://highered.mheducation.com/novella/mixquizprocessingservlet https://www.youtube.com/watch?v=eds_nmrppkc&ebc=anypxkoelk36eu gojcthiihfm77sbmkzmmc7riq1mfxjsyitkml2ng85mqrgewaxysxxcncuc 7h2zSGRTAgUwaL38KLsE2qbaQ https://www.youtube.com/watch?v=d7dgsxlborg

General characteristics of Phylum Ctenophora 1) Biradial symmetry in most spp. 2) Ellipsoidal body shape 3) Mostly triploblastic 4) Only one sp. having cnidocytes w/ nematocysts; All spp. have coloblasts = adhesive cells. 5) GVC (gastrovascular cavity) 6) Statocyst sense organs : controlling equilibrium. 7) No polymorphism. 8) Reproduction sexually in monoecious individuals (both male and female sex cells produced by some individuals. 9) Luminescence (biochemical light production process involving enzymatic hydrolysis of ATP).