Phylum Cnidaria
By: Brayden Singleton, Christian Whiting
What is a Cnidaria?
A Cnidaria is exclusively found in marine life supporting environments. They are typically found in freshwater or saltwater. What distinguishes a cnidaria is their specialized cells called Cnidocysts. Cnidocysts are mainly used for capturing prey. Cnidaria also have two main cell layers. They also have a hydrostatic skeleton which means that their skeleton is supported by fluids.
Box Jellyfish
Higher Classification Name: Medusoza
Sea Anemone
Higher Classification Name: Hexacorallia
Velella
Higher Classification Name: Chondrophore
Characteristics of a Cnidaria Orginism
Cnidarians are characterized by the presence of three tissue layers, an outer protective epidermis, a middle layer called the mesoglea, and an inner layer called the gastrodermis, Cnidarians possess only one digestive opening, which serves as both the mouth and the anus. It known as the gastrovascular cavity. Cnidarians feed using tentacles that are embedded with stinging nematocysts.
Nervous System
Cnidaria do not have a brain or nervous system but in fact have neural tissue that is considered to be some form of centralization. Their body is made up of nerve nets that control their movement. Most of their neurons have combined characteristics which are motor, sensory and much more which make the neurons multifunctional.
Reproduction
Cnidaria can reproduce sexually and asexually. For sexual reproduction, Cnidarian larvae grow up and gain tentacles which then split horizontally into a series of disks that become juvenile medusae. The males release sperm and ova from their gastrodermis, into the water during breeding season. Asexually, Cnidaria can regenerate after fragmentation.
Portuguese Man o' War
Higher Classification Name: Physalia
Digestion and Eating
Unlike most animals, Cnidaria have 1 gastrovascular cavity which means that they eat and get rid of waste through the same hole. Most Cnidaria are big enough to eat small fish, but the Hydra is not big enough to eat those fish. They eat smaller organisms like plankton and brine shrimp.
Movement
Cnidaria do not move at all when they are adults. When Cnidaria are young, they move a short distance and after, never move again. Some children Cnidaria use jet propulsion while others attach themselves to seaweed in a wave current and capture prey on the spot.
Special Adaptations
Cnidaria have tentacles that capture and subdue their prey by stinging the prey. The sting cells are called cnidocytes which contain a thread-like stinger called the nematocyst. A Cnidaria is either a polypoid or medusoid. A polypoid has tentacles and usually has its mouth facing upward while a medusoid has tentacles and its mouth is facing down.
Excretion
Cnidaria get rid of waste they eat through. Their mouth is a hole through a two layered-body. Cnidaria get rid of waste through diffusion. Their waste is either dissolvable or non-dissolvable.
Circulation
Cnidaria don’t have a circulation system because their cells are in tack with water. Water contains oxygen and nutrients which makes a circulation system not needed for Cnidaria.
Fun Facts
The Box Jellyfish is the most dangerous Cnidaria in the world
Portuguese Man ‘o’ War have toxins on their body that paralyze and kill fish
A Lion’s Mane Jellyfish can grow up to 120 ft
Fish is the most common food for Cnidaria
Lion’s Mane Jellyfish can live up to 1 year
There’s about 1270-1770 different types of Cnidaria organisms
There are 4 main types of Cnidarians: Anthozoa, Scyphozoa, Cubozoa and Hydrozoa
- Marine Turtles, the Crown of Thorns Starfish are predators of Cnidarian organisms
- Cnidaria only live in marine aquatic environments and sometimes in fresh water
- Cnidaria are symmetrical no matter what
Lion's Mane Jellyfish
Higher Classification Name: Cyanea
Work Cited
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National Library of Medicine, n.d. Web. 08 May 2017.
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