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 – Scyphozoa Cubozoa 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=-Tp38DUjUnM

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=Szt42nG-hGg

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 Fission Pedal Laceration Polyp continued – 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=8zSZtZDwabo

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/4ykESFPhBVo

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=bPbQs4Zc85k

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=aJUuotjE3u8

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 ..\Animals\Darwin's Jellyfish\Darwin’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=uIf0kRpkQ_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=1aX61LzmeYA

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