Cnidaria - Jellyfish & Anemones

> Phylum: Cnidaria          Hatschek, 1888

Etymology

• From the Greek word “Cnidos” means stinging nettle

General                                                       

• Containing over 9,000 species (MESC 2021)
• Oldest clade of animals with ‘true tissue’
• Includes corals, hydras, jellyfish, Portuguese men-of-war, sea anemones, sea pens, sea whips and sea fans

Distribution

• Found all around the Earths oceans
• All Aquatic, mostly marine approximately 20 freshwater species (Hydra) (MESC 2021)
• Ranging from shallow coastal waters to deep ocean floors

Habitat

• Some are solitary (sea anemones), some conical (corals)
• Some are sessile (fixed to a substance) or free-swimming
• Range from coral reefs, rocky shores, and the open water column

Defining Characteristics

• Stinging soft bodied invertebrates
• Presence of cnidoblasts with stinging nematocysts on the tentacles
• Mostly radially symmetry, however sea anemones exhibit biradial symmetry, some exceptions eg. blue bottle
• Diploblastic animals and show tissue level (grade) of organization
• Polymorphism and have two body forms, i.e. polyp and medusa
• Made up of 98% water
• Exoskeleton chitinous (perisarc) or calcareous (corals)

Phylum Cnidaria can be divided into: 

Subclass          Anthozoa       Anemones & Corals     

Subclass          Hydrozoa          Hydras & Portuguese Man of Wars

Subclass          Cubozoa          Box Jellyfish

Subclass:     Anthozoa          True Corals, Sea Anemones & Sea Pens                                                                                                                                                

Class:     Hexacorallia

Order:     Actiniaria          Sea Anemones

Order:     Antopatharia          Black Corals and Thorny Corals

Order:     Ceriantharia          Tube-Dwelling Anemones

Family:     Cerianthidae

Genus:     Cerianthus

Cerianthus sp. _ Tube Dwelling Anemones 

Photo taken Puerto Galera Philippines on 10/10/2022

Order:     Corallimorpharia          

Order:     Scleractinia          Stony Corals

Order:     Zoantharia          Zoanthids

Class: Octocoraliia

Phlyctenactis tuberculosa_Wandering Sea Anemone            Phlyctenactis tuberculosa_Wandering Sea Anemone                       

Photo taken at Flinders Pier 29.11.2014                                              Photo taken at Flinders Pier 07.02.2015

Edwardsia vivipar  

Photo taken at Blairgowrie Pier 17.08.2013

Actinia tenebrosa, Waratah Anemone                                                                     Actinia veratra, Anemone

Photo taken at Barwon Heads 01.10.2018                                                                           Photo taken at Queenscliff Labs 01.10.2018                 Photo taken at Barwon Heads 01.10.2018

Photo taken at Mornington Pier 01.10.2018   

Anemonactis clavus, Anemone

Photo taken at Rye Pier 02.10.2021

CLASS: Hydrozoa

Hydras & Portuguese Man of Wars

Tubulariidae sp.

Photo taken Flinders Pier 27.09.2021

CLASS: Scyphozoa

Moon Jellfish & Purple jellyfish

Pseudorhiza haeckeli_Haeckel's Jelly                             Lion’s Mane jellyfish, Cyanea Annaskala

Photo                                                                                                             Photo taken at Ranelagh Reef