Phylum Cnidaria Phylum Cnidaria Examples Sea anemones Corals

Phylum Cnidaria

Phylum Cnidaria Examples: �Sea anemones �Corals �Sea Pen �Sea Fan �Sea Plume �Hydra �Jelly fish �Portuguese Man o’ War �Box Jelly Fish

Cnidaria �(nettle like or connected with) �relatively simple animals �Level of Organization: �cells & tissue �No true organs �most are sessile, �those that are unattached (such as jellyfish) can swim only feebly �More than 9000 species

Cnidaria �Mostly found in shallow marine habitats, �especially in warm temperatures and tropical regions �few in fresh water �Little economic importance �Neurotoxins in medical research �Coral – jewelry, building, reefs �Coral reefs �habitat for many �great biodiversity �protect coastline �Symbiosis with other organisms

Phylum Cnidaria �Phylum includes branching, plantlike hydroids; flowerlike sea anemones; jellyfishes; gorgonian corals; stony corals �Symbiotic relationships �Algae frequently live in a mutualistic relationship in the tissues of cnidarians �Fish living within tentacles of a Portuguese man of war �Sea anemone & clown fish

Phylum Cnidaria �Four classes of Cnidaria: �Hydrozoa – �the most variable class including hydroids, fire corals, Portuguese man-of-war, and others �Scyphozoa �“true” jellyfishes �Cubozoa �cube jellyfishes �Anthozoa �the largest class; includes sea anemones, stony corals, and others

Form and Function � All cnidarian forms fit into one of two morphological types (dimorphism): a polyp or a medusa �Polyp – a hydroid form which is adapted to a sedentary or sessile life �Medusa – a jellyfish form which is adapted for a floating or free-swimming existence

Form and Function �Polyp – �Most have tubular bodies �A mouth surrounded by tentacles defines the oral end of the body �Mouth leads into a blind gut or gastrovascular cavity �Aboral end of the polyp is usually attached to a substratum by a pedal disc or other device

Form and Function �Medusae – �usually free swimming �bell-shaped or umbrella-shaped bodies �tetramerous symmetry �body parts arranged in fours �Mouth is usually centered on the concave side �Tentacles extend form the rim of the umbrella �Are essentially an unattached polyp with the tubular portion widening and flattening into the bell shape

Body Wall �body wall surrounding the gastrovascular cavity consists of: �an outer epidermis �an inner gastrodermis �with mesoglea between them �Cnidocytes are found throughout the epidermis

Cnidocytes �Explosive cell containing one giant secretory organelle or cnida �(plural cnidae) �Used for prey capture and defense from predators. �A cnidocyte fires a structure that contains the toxin, from a characteristic sub-cellular organelle called a cnidocyst �(also known as a cnida or nematocyst). �This is responsible for the stings delivered by jellyfish �http: //www. youtube. com/watch? v=-Tp 38 DUj. Un. M

Cnidocytes �They have three functions �Penetrate prey and inject poison �Recoil and entangle prey �Secrete an adhesive substance used in locomotion and attachment (glutinants) Note = most are not harmful to humans, however Portuguese man-of-war and certain jellyfish are quite painful and sometimes dangerous

Cnidocytes

Locomotion �Hydras can move about freely by gliding on their basal disc, aided by mucus secretions �They can also use a “measuring worm” movement, looping along a surface by bending over and attaching their tentacles to the substratum �Medusae – can move freely and swim by contracting the bell, expelling water from the concave, oral side �http: //www. youtube. com/watch? v=Szt 42 n. G-h. Gg

Reproduction Polyps �Budding – a knob of tissue forms on the side of an existing polyp and develops a functional mouth and tentacles �Bud that detaches from the polyp is a clone �When buds do not detach, a colony forms and food may be shared through a common gastrovascular cavity

Reproduction Polyp continued – �Fission �one-half of a polyp pulls away from the other �Pedal Laceration �tissue torn from the pedal disc develops into new, tiny polyps

Reproduction �Sexual �Medusae release sperm & eggs �Some monoecious, some dioecious �Monoecious = “one house” �Dioecious = “two houses” (separate sexes) �Larvae free-swimming �http: //www. youtube. com/watch? v=8 z. SZt. ZDwabo

Life Cycles �polyps and medusae play different roles �in general a zygote develops into a free-swimming planula larva �the planula settles and metamorphoses into a polyp �a polyp makes other polyps asexually, �polyps in Hydrozoa and Scyphozoa eventually make medusae �Medusae (made asexually) develop into either male or female individuals and produce gametes �Fertilization typically occurs in open water

Feeding and Digestion �the mouth opens into the gastrovascular cavity �digestion is started in the gastrovascular cavity (extracellular digestion) by enzymes discharged by gland cells �nutritive-muscular cells phagocytize many food particles for intercellular digestion �http: //youtu. be/4 yk. ESFPh. BVo

Class Hydrozoa �most are marine and colonial in form �found throughout the world, with 16 species occurring in North America �Hydra �(freshwater – normal habitat is underside of aquatic leaves and lily pads in cool, clean fresh water of pools and streams)

Portuguese man-of-war

Portuguese man-of-war https: //www. youtube. com/watch? v=b. Pb. Qs 4 Zc 85 k

Portuguese man-of-war attack

Class Scyphozoa �includes most of the larger jellyfish (cup animals) �most range from 2 to 40 cm in diameter (may attain a bell over 2 m in diameter and tentacles 60 to 70 m long) �the bell can vary from a shallow saucer to a deep helmet of goblet shape �range in color from colorless to bright orange and pink �https: //www. youtube. com/watch? v=a. JUuotj. E 3 u 8

Giant jellyfish

Giant Jellyfish

Northern Sea Nettle �common in near surface waters off the West Coast of the USA, as well as from Japan to the Bering Sea

Darwin’s Jellyfish �. . AnimalsDarwin's JellyfishDarwin’s Jellyfish. ppt

Class Cubozoa �bells are almost square �a tentacle or group of tentacles if found at each corner of the square at the umbrella margin �strong swimmers and fierce predators, feeding mostly on fish

Carybdea

Carybdea

C. fleckeri

C. fleckeri

Box Jelly or Sea Wasp (lethal)

Box Jelly Video https: //www. youtube. com/watch? v=u. If 0 k. Rpk. Q_0

Sting of a Sea Wasp �The venom has cardiotoxic, neurotoxic and highly dermatonecrotic components

Class Anthozoa �“flower animals” �No medusa stage �Found in both shallow and deep water, polar as well as tropical seas �There are three subclasses �Zoantharia (sea anemones, hard corals, and others) �Ceriantipatharia (tube anemones, thorny corals) �Octocorallia (sea fans, sea pens, sea pansies)

Zoantharia – sea anomone

Zoantharia – sea anomone

Zoantharia – coral reef

A Closer Look at Coral https: //www. youtube. com/watch? v=1 a. X 61 Lzme. YA

Ceriantipatharia – Tube anemone

Ceriantipatharia – Tube anemone

Ceriantipatharia – Tube anemone

Octocorallia – sea pens

Octocorallia – sea pens

Octocorallia – sea pens

Ctenophores �phylum contains fewer than 100 species �all are marine in all seas, but most especially in warm waters �they take their names from eight rows of comblike plates used for locomotion �common names are “sea walnuts” and “comb jellies” �most are free-swimming and are common in surface waters �the fragile, transparent bodies are easily seen at night when they emit light (luminescent)

Comb jellies

Comb jelly

Comb jelly

Beroe cucumis

Beroe

Comb jelly