Zoo - Lab: Phylum Porifera Flashcards

Questions and Answers

What is visible when you look at a sponge?

Its skeleton; all cells are gone.

What are metazoans?

Multicelled animals.

What are choanoflagellates?

Protists that are the closest living relatives of animals.

What does the colonial flagellate hypothesis state?

Animals are descended from an ancestor that resembled a hollow spherical colony of flagellated cells. Signup and view all the answers

What are the characteristics of sponge evolution?

They belong to Phylum Porifera, are the simplest metazoans, and are similar to choanoflagellates. Signup and view all the answers

What is the sponge growth form like?

Very simple, amorphous in shape, asymmetrical, with no true tissues. Signup and view all the answers

What are the four classes of sponges?

Homoscieromorpha, Calcarea, Demospongiae, Hexactinellida. Signup and view all the answers

What characteristics is sponge classification based on?

Spicules structure, spongin presence/absence, canal systems. Signup and view all the answers

What are spicules?

The support structures making up the skeletal framework of the sponge. Signup and view all the answers

What is the function of sclerocyte cells?

They secrete spicules. Signup and view all the answers

What is spongin?

A fibrous protein component of the skeletal framework of a sponge. Signup and view all the answers

How do sponges feed?

They filter food particles out of water that is pumped through canals. Signup and view all the answers

What is the order of water movement through the sponge's canal system?

Dermal ostia > choanocytes > osculum. Signup and view all the answers

What are dermal ostia?

Incurrent pores for the sponge in all canal systems. Signup and view all the answers

What are choanocytes?

Collar cells that line the body cavity and have flagella that circulate water. Signup and view all the answers

What is the osculum?

A large opening through which filtered water is expelled. Signup and view all the answers

What is the spongocoel?

The large central and internal cavity of the sponge. Signup and view all the answers

What is characteristic of asconoid sponges?

Simple vase-like structure with a single osculum. Signup and view all the answers

What is the water path in asconoid sponges?

Dermal ostia > choanocytes > spongocoel > osculum. Signup and view all the answers

What are syconoid sponges?

Sponges with folded body walls forming incurrent canals. Signup and view all the answers

What is the water path in syconoid sponges?

Dermal ostia > incurrent canal > prosopyles > radial canals > apopyles > spongocoel > osculum. Signup and view all the answers

What advantages does the folding of the body wall give syconoid sponges?

Increases surface area for filtering and feeding. Signup and view all the answers

What is the leuconoid canal system?

The most complex sponge system with incurrent canals leading to flagellated chambers. Signup and view all the answers

What advantages does the leuconoid canal system provide over other systems?

More flagellated chambers lined with choanocytes allow for increased pumping and filtering. Signup and view all the answers

How do adult sponges colonize new habitats despite being sessile?

They reproduce both sexually and asexually, allowing larvae to swim to new locations. Signup and view all the answers

How might changes in sponge population affect other organisms in coral reefs?

A decrease in sponge population may lead to increased predation on organisms that rely on sponges for shelter. Signup and view all the answers

What is an argument against the colonial flagellate hypothesis?

Choanocytes do not adhere to each other like choanoflagellates do. Signup and view all the answers

How would an abnormally small prosopyle and large apopyle affect a syconoid sponge's filtering ability?

It would reduce oxygen entry and limit filtering effectiveness. Signup and view all the answers

Describe two features that Phylum Porifera and Phylum Placozoa have in common.

Both are metazoans and exhibit asymmetry. Signup and view all the answers

Study Notes

Phylum Porifera: Sponges Overview

Sponges are part of Phylum Porifera, characterized by their simplicity and lack of true tissues.
They resemble choanoflagellates, indicating evolutionary connections.
Adult sponges are sessile, relying on gametes and larvae for reproduction and colonization.

Sponge Structure and Composition

Sponge skeletons consist of support structures called spicules, secreted by sclerocyte cells.
Spicules can be siliceous (made of silica) or calcareous (made of calcium carbonate).
Spongin is a fibrous protein that contributes to the sponge's skeletal framework.

Sponge Forms and Classes

Sponge bodyforms vary in complexity, including asconoid, syconoid, and leuconoid structures.
Four main classes of sponges: Homoscieromorpha, Calcarea, Demospongiae, Hexactinellida.
Sponge classification is based on spicule structure, presence of spongin, and canal system type.

Canal Systems

All sponges use canal systems to filter water for feeding: dermal ostia > choanocytes > osculum.
Asconoid sponges have a simple vase-like structure with a single osculum; they have choanocytes lining the spongocoel.
Syconoid sponges have folded body walls creating incurrent and radial canals for better water filtration.
Leuconoid sponges are the most complex, with multiple flagellated chambers leading to excurrent canals.

Water Movement in Sponges

Asconoid water path: dermal ostia > choanocytes > spongocoel > osculum.
Syconoid water path: dermal ostia > incurrent canal > prosopyles > radial canals > apopyles > spongocoel > osculum.
Leuconoid water path: dermal ostia > incurrent canal > prosopyles > flagellated chambers > excurrent canals > osculum.

Habitat and Ecosystem Impact

Sponges provide essential habitats for various marine species and can affect community dynamics through their population changes.
A decrease in sponge populations can lead to reduced shelter for smaller organisms and loss of food resources for sponge-eating fish.

Evolutionary Connection

Choanoflagellates are considered closely related to sponges, supporting the colonial flagellate hypothesis that suggests an ancestral form resembling a colony of flagellated cells.

Abnormal Structures and Their Effects

Abnormalities in sponge structures, such as small prosopyles or large apopyles, can reduce oxygen intake and filter efficiency, impacting feeding capabilities.

Similarities Between Porifera and Placozoa

Both phyla exhibit characteristics like metazoan status, asymmetry, and amorphous shapes, as well as infoldings in their epithelial structures.

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Description

Explore the fundamental concepts of Phylum Porifera with these flashcards. Engage with key terms like sponges, metazoans, and choanoflagellates to deepen your understanding of this unique group of organisms. Perfect for classroom study or quick revision.