Cnidarians and Ctenophores

Cnidarians and Ctenophores

Characteristics All carnivorous Contain a jelly-like layer between epidermis and gastrodermis called mesoglea Single opening (mouth/anus) to gastrovascular cavity where food & water enter & wastes leave; called twoway digestive system Have a oral surface (mouth/anus) and an aboral surface (opposite)

Characteristics Have tentacles around mouth to pull in water & capture food Have a simple nerve net with to help with movement & senses

Characteristics Sessile members include corals, sea anemones, & sea fans Motile members include jellyfish and Portuguese man-of-war Have radial symmetry as adults

Characteristics Contain stinging cells called cnidocytes in their tentacles that contain coiled stingers called nematocysts that can shoot out & paralyze prey

Cnidocyte with nematocyst Trigger hair coiled thread Undischarged Discharged

Body Plan have 2 basic body forms: polyp and medusa

Body Plan polyp forms are usually sessile with upright tentacles arranged around the mouth at the top (oral) and with a thin layer of mesoglea Polyps are the asexual stage Corals, hydra, & sea anemones exist in the polyp form as adults

Body Plan Medusa forms are usually free-swimming, bellshaped animals with tentacles that hang down around the mouth Medusa are the sexual stage Jellyfish & Portuguese man-of-war are medusa form as adults

Gastrovascular Cavity = Blue Gastrodermis = Green Epidermis = Black Mesoglea = Red

Body Plan Some cnidarians are dimorphic or go through both polyp & medusa stages in their life cycle planula larva free-swimming, flattened, ciliated, fertilized egg strobila the chain of segments of the larva of a jellyfish, each segment of which gives rise to a freeswimming medusa. ephyra swimming stage of medusa after detaching from strobila

Body Plan Some are solitary (Hydra) others are colonial (corals) Three classes include Hydrozoa (hydra), Scyphozoa (jellyfish), & Anthozoa (sea anemones & corals)

Class Hydrozoa sessile hydra (exists only as polyps) Portuguese man-of-war (exists as colony of polyps & medusa) Group of cells called basal disk produces sticky secretion for attachment & can secrete gas bubbles to unattach & let hydra float

Class Hydrozoa Hydra also move by somersaulting (tentacles bend over to bottom as basal disk pulls free) Tentacles pull food into gastrovascular cavity where enzymes digest it Reproduce asexually by budding during warm weather & sexually in the fall Hermaphrodites that release sperm into water to fertilize eggs of another hydra http://youtu.be/-ui531gmrtm

Class Hydrozoa Polyp Forms Hydra littoralis Medusa Forms Obelia Portuguese man-of-war (Physalia physalis)

Class Scyphozoa Includes bell-shaped jellyfish Medusa stage is dominant in the life cycle tentacles may be meters in length & carry poisons that cause severe pain or death Have both asexual polyps & sexual medusa stages in their life cycles

Class Scyphozoa Cyanea capillata (Lion s Mane)

Class Scyphozoa Aurelia aurita (Moon Jellyfish)

Class Scyphozoa Cephea cephea (Cauliflower Jellyfish)

Class Scyphozoa Olindias formosa (Flower Hat Jellyfish)

Class Scyphozoa Chrysaora fuscescens (Pacific Sea Nettle)

Called "flower animals" Class Anthozoa Some anemones in the Pacific Ocean live symbiotically with the clownfish sharing food & protecting each other Sea anemone is a sessile, polyp-form that uses its tentacles to paralyze fish and the only solitary form

Class Anthozoa Stony Corals (Branching Coral and Doming Coral)

Class Anthozoa Soft corals

Class Anthozoa Gorgonians (Sea Whips and Sea Fans)

Class Anthozoa Sea Pens

Class Anthozoa Sea Pansies

Includes comb jellies Phylum Ctenophora Have eight rows of fused cilia called "comb rows and is the largest animal to move by cilia

Phylum Ctenophora Lack cnidocytes but have cells sticky cells called colloblasts that bind to prey Colloblasts located on two ribbon-like tentacles Have sensory structure called apical organ to detect direction in the water Most are hermaphrodites (make eggs & sperm) Produce light by bioluminescence

Phylum Ctenophora Chironex fleckeri (Sea Wasps)

Phylum Ctenophora Pleurobrachia (Sea Gooseberry)

Phylum Ctenophora Box Jellyfish

Monster Quest: Killer Jellyfish 1. How did the Nomura jellyfish affect the power plant? 2. Describe the physical characteristics of the jellyfish. 3. Name one theory why the Nomura jellyfish took over the sea of Japan. 4. KEY FACT 5. KEY FACT 6. KEY FACT 7. KEY FACT