Cnidaria/Ctenophora Flashcards
(46 cards)
What are the two tissue types of cnidarians?
Gastrodermis and epidermis.
What are the main taxonomic features of phylum cnidaria?
They possess a cell called cnidocytes, which contain an organelle called a cnidocyst (e.g. a nematocyst). They come in various forms; can inject poison or attach to the prey. They have a high taxonomical importance. They’re used to capture prey or for defence.
What are the two body forms of cnidarians?
Polyps and medusa.
What is the gastrovascular cavity?
The blind-sac gut.
What is the mesoglea?
A gelatinous protein layer between the epidermis and the gastrodermis.
What kind of body plan do all cnidarians have?
A radially symmetrical body plan.
What is a nerve net?
A diffuse mesh of nerve cells that take part in simple reflex pathways. Nerve cells interact with sensory and contractile cells. Epitheliomuscular cells work in coordination with the nerve net. There is no brain/CNS.
What are statocysts?
Cells that are able to sense gravity.
What are the four classes within the phylum cnidaria?
Hydrozoa, Scyphozoa, [Cubozoa], Anthozoa.
What is contained within the class Hydrozoa?
Portuguese man o’ war, hydra, and other medusas.
What is contained within the class Scyphozoa?
Includes the true jellyfish.
Stauromedusae - stalk jellyfish.
Coronatae - deep sea primarily.
Semaeostomeae - common and moon jellyfish, lion’s mane.
Rhizostomae - barrel jellyfish (big, solid, can be eaten).
What is contained within the class Cubozoa?
The cubomedusae, the box jellyfish and sea wasps [incredibly toxic and dangerous to humans].
What is within the class Anthozoa?
Corals, sea fans and sea pens.
Ceriantipatharia
Alcyonaria=octocorallia [octocorals]
Zoantharia=Hexacorallia. [Anemones and true corals].
What are the two subphyla?
Medusozoa and Anthozoa - not often used apart from true jellyfish nerds.
What are the general features of class Hydrozoa?
The medusa have a velum ‘skirt’ and nerve ring. The asexual polypoid body form is the dominant part of the life cycle with specified buds for reproducing/feeding. Reproductive buds tend not to have tentacles. There are thousands of species.
What is the life cycle of Hydrozoa?
Sexually reproducing medusa produce eggs & sperm.
A fertilised egg becomes a non-feeding (lecithotrophic) planula.
This then becomes a young polyp colony, which is the asexual part of the life cycle.
This polyp produces new medusa through budding.
What do the hydromedusae often do?
Be fluorescent? They can also have a protruding mouthpart resembling a tentacle.
What are the hydrocorals?
They are hydroids that form hard skeletons, for example Millepora the fire coral.
In class Hydrozoa, what are siphonophores?
Siphonophores are gelatinous, fragile, colonial organisms. They are made up of specialised individuals. They lack a benthic phase. There are three groups and the organisation of the colony defines which group.
What are the types of individual polyps found in siphonophores?
They all start with a pneumatophore which is a gas filled float. They may also have nectophores (swimmming structures), siphosomal growth zones, gastrozooids, gonozooids, and dacctylzooids (for defence).
What are the three groups of siphonophores?
Physonects
Cystonects (no nectophores)
Calycophorans (no nematophores)
What is a Portuguese man o’ war and a by the wind sailor?
A siphonophore with a large pneumatophore and very specialised polyps.
A siphonophore that lives at the boundary between sea and air - a neuston.
What are the defining features of class Cubozoa?
They have a cuboid shape and the margin of the bell is NOT scalloped.
They have a velarium (a flap of tissue on the underside of the bell)
Rhopalium has complex eyes with lenses.
They are VERY poisonous.
What are the two types of Cubozoa and what are their defining characteristics?
Carybdeids - one tentacle per pedalium (corner)
Chirodropids - multiple tentacles per pedalium.
