Biology Class: Anthozoa Characteristics

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Questions and Answers

What is the characteristic of the gastrovascular cavity in Anthozoa?

It serves only digestive functions.

It is absent in Sea anemones.

It is a single compartment.

It is divided into compartments. (correct)

What is the function of the stomodeum in embryonic development?

It forms the anus opening.

It forms the circulatory system.

It forms the digestive system.

It forms the mouth opening. (correct)

What is the characteristic of Sea anemones compared to Hydras?

They have more tentacles. (correct)

They have a single polyp.

They have a shorter body.

They have longer tentacles.

What type of reproduction is characteristic of Anthozoa?

Both sexual and asexual reproduction. Signup and view all the answers

What is the characteristic of Hermatypic Corals?

They are reef-forming and actively build corals. Signup and view all the answers

What is the characteristic of Scleractinia (hard stony corals)?

They appeared in the mid-Triassic. Signup and view all the answers

Why can Scleractinia easily form fossils?

Because they have an exoskeleton. Signup and view all the answers

What is the phylogenetic position of Anthozoa?

They are phylogenetically basal. Signup and view all the answers

What is the characteristic of the primary or complete mesentery?

Both ends are attached to the body wall and the pharynx wall Signup and view all the answers

Which of the following is NOT a characteristic of Hexacoralia?

Their gastrodermal muscles are organized in bunches Signup and view all the answers

What is the function of Cnidae in Actiniaria?

To capture prey through stinging Signup and view all the answers

Which of the following is a characteristic of Ceriantharia?

They are capable of making their own tube Signup and view all the answers

What is the characteristic of the tertiary mesentery?

One end is attached to the body wall and the other end is free Signup and view all the answers

What is the characteristic of the gastrodermal muscles in Anthozoa?

Not organized in bunches Signup and view all the answers

Which of the following has nematocysts inside their body?

Sea Anemone Signup and view all the answers

What type of symmetry do Hexacoralia have, except for Ceriantharia?

Biradial symmetry Signup and view all the answers

What is the main reason why the relationship between the hermit crab and the anemone is not symbiotic?

The anemone does not live inside the hermit crab's tissues Signup and view all the answers

What is the function of the Siphonoglyph in Cnidarians?

To direct water flow for respiration Signup and view all the answers

What is the term for the type of skeleton found in some Cnidarians?

Calcareous skeleton Signup and view all the answers

Which of the following is a characteristic of Order Actinaria?

They have a solitary polyp Signup and view all the answers

What is the term for the ability to form coral reefs?

Hermatypic Signup and view all the answers

Which of the following is a characteristic of Family Actiniidae?

They have extratentacular budding Signup and view all the answers

What is the function of Verrucae in Family Actiniidae?

To avoid desiccation Signup and view all the answers

What is the term for the type of reproduction where buds are produced outside the tentacles?

Extratentacular budding Signup and view all the answers

What is the composition of the skeleton in Scleractinia corals?

Aragonite Signup and view all the answers

What is the term for the whole colony in Scleractinia corals?

Corallum Signup and view all the answers

What is unique about the Scleractinia coral's symbiotic relationship with algae?

Obligate Symbiosis Signup and view all the answers

What is the name of the coral-like anemones that belong to the order Corallimorpharia?

Coral-Like Anemones Signup and view all the answers

What is the approximate percentage of Corallimorpharia that harbor Zooxanthellae?

48.2% Signup and view all the answers

What is unique about the skeleton of Antipatharia corals?

It is black or dark brown in color Signup and view all the answers

What is the characteristic number of tentacles and mesenteries in Antipatharia corals?

8 or multiples of 8 Signup and view all the answers

What is a characteristic of the polyps in Octocorallia?

They are embedded in a matrix of mesogleal tissues Signup and view all the answers

What is unique about the way sea pens feed?

They feed off of plankton Signup and view all the answers

What is the characteristic of the colony in Suborder Sessiliflorae?

It is made up of a flattened heart shaped structure called rachis and a stem Signup and view all the answers

What is the characteristic of the larvae of Subclass Ceriantharia?

They are temporarily planktonic and free-swimming Signup and view all the answers

Why can't the tentacles of Subclass Ceriantharia retract into the column?

They have no sphincter muscles Signup and view all the answers

What type of cnidae do Subclass Ceriantharia have?

Spirocysts, Atrichs, Holotrichs, and Mastigophores Signup and view all the answers

What is the body shape of Subclass Ceriantharia?

Elongated Signup and view all the answers

What do Subclass Ceriantharia use their tubes for?

For various purposes, including protection, shelter, feeding, and reproduction Signup and view all the answers

How many whorls of tentacles do Subclass Ceriantharia have?

Two Signup and view all the answers

Study Notes

Class Anthozoa

Polypoid body form, with no medusa stage
Gastrovascular cavity is septate, with septa called mesentery
Mouth is slit-like, with a stomodeum (invagination or depression that forms the mouth opening during embryonic development)
They have both colonial and solitary polyp forms
Reproduction is both sexual (through planula) and asexual (through budding and fission)

Structure of a Sea Anemone

Sea anemones are shorter and stouter than Hydras
They have more tentacles than Hydras, but Hydras have longer tentacles
They have a septate gastrovascular cavity
Some are hermatypic, meaning they are reef-forming Anthozoans that actively build corals

Phylogeny of Anthozoa

Reconstruction of key morphological characters in Cnidaria based on phylogenetic hypothesis
Hexacoralia have biradial symmetry, except Ceriantharia, which make their own tube
Gastrodermal muscles are not organized in bunches
Symmetry is biradial, except for Ceriantharia

Defining Characteristics

They are polypoid, with the polyp being the dominant form
No medusa stage
Gastrovascular cavity is septate
Septa is called mesentery
Mouth is slit-like with pharynx called stomodeum
Stomodeum leads into gastrovascular cavity, serving both digestive and circulatory functions

Modes of Colony Formation

Meandrina - brain coral
Siphonoglyph - specialized ciliated groove or furrow found in the pharynx to direct water flow
Zooxanthellae - brown algae that live symbiotically with Cnidarians

Orders of Anthozoa

Order Actiniaria - true sea anemones, with column-shaped bodies topped by an oral disk
Order Zoanthidea - partly chitinous with leathery tissues, mostly colonial, with zooxanthellae
Order Scleractinia - hard corals, with skeletons made of aragonite, living in shallow to deep water
Order Corallimorpharia - coral-like anemones, solitary or aggregated polyps, without stony skeleton
Order Antipatharia - soft, deep water corals, with chitin skeleton, colonial
Order Octocorallia - blue corals, soft corals, sea pens, and gorgonians, with polyps embedded in a matrix of mesogleal tissues

Subclass Octocorallia

Sea pens, all colonial, some resemble antique quill pens, others are club-like or radiating
Suborder Subselliflorae - sea pens, cosmopolitan, develops a single polyp that becomes the rachis from which other specialized polyps arise
Suborder Sessiliflorae - sea pansies, colonial, fleshy and leaf-shaped, living on sandy or muddy sediment

Subclass Ceriantharia

Tube dwellers, constructing or inhabiting tubes for protection, shelter, feeding, and reproduction
Body is elongated, with two whorls of tentacles, where the outermost is longer
Larvae are planktonic and free-swimming
Tentacles are not retractable into the column due to the lack of sphincter muscles

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Description

Learn about the defining characteristics of Class Anthozoa, including their polypoid form, septate gastrovascular cavity, and more.