Porifera (Sponges) Overview
10 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is a key characteristic that distinguishes true metazoa from the cells described?

  • Absence of coordination between cell groups
  • Ability to form true tissues
  • Formation of germ layers (correct)
  • Presence of cellular specialization

Which statement best describes the coordination of activities among the cell groups mentioned?

  • The cells work independently but form structures resembling tissues.
  • There is no coordination between the activities of the cell groups. (correct)
  • There is a high degree of coordination among the cells.
  • The cells coordinate their activities to form tissues.

Why are the cells described in the content not considered true tissues?

  • They are not organized into germ layers. (correct)
  • They do not have distinct cell types.
  • They exhibit a high level of specialization.
  • They do not function independently.

What aspect of the cells implies a lack of true multicellularity?

<p>Lack of coordination among cell groups (A)</p> Signup and view all the answers

Which statement about the cells described is not true?

<p>They form distinct tissues. (C)</p> Signup and view all the answers

What characteristic defines the phylum that contains sponges?

<p>Presence of pores (C)</p> Signup and view all the answers

In the evolutionary tree of animals, sponges are considered to be what in relation to other animals?

<p>The sister group of all other animals (D)</p> Signup and view all the answers

Which statement is true regarding the phylogeny of sponges?

<p>They lack any form of tissue organization. (D)</p> Signup and view all the answers

What distinguishes sponges from all other animal groups?

<p>Their body structure with pores (D)</p> Signup and view all the answers

Which of the following is the closest description of sponges within the context of animal evolution?

<p>The first to evolve from multicellular ancestors (C)</p> Signup and view all the answers

Flashcards

Porifera phylum

A phylum containing sponges.

Sponges

Animals that belong to the Porifera phylum.

Evolutionary Tree

A diagram showing the branching order of species.

Last common ancestor

An ancestral organism from which all other species in a group descend.

Signup and view all the flashcards

Sister group

Closely related group of organisms.

Signup and view all the flashcards

Cellular Specialization

Cells develop different structures and functions within a multicellular organism

Signup and view all the flashcards

Germ Layers

Early embryonic tissue layers that give rise to specific organs, an essential feature of true animals

Signup and view all the flashcards

True Tissues

Groups of specialized cells that work together and coordinate functions in a multicellular organism

Signup and view all the flashcards

Metazoa

Multicellular animals

Signup and view all the flashcards

No Coordination Between Cell Groups

Cells in simple organisms do not have organized communication or shared function

Signup and view all the flashcards

Study Notes

Porifera (Sponges)

  • Phylum Porifera is part of the Kingdom Animalia.
  • Sponges are placed in the Parazoa group due to their evolutionary difference from protozoa and metazoa.
  • They are multicellular but lack true tissues.
  • Sponges are mostly marine, but some live in freshwater.
  • They come in various shapes (spherical, flat, vase-shaped, irregular).
  • Color variations include red, yellow, orange, purple, green, and black.
  • Symmetry is typically radial in primitive species, but most are asymmetrical.
  • The body wall is pierced by tiny pores (ostia) that lead to channels.
  • A prominent feature is the oscula (exhalant openings).
  • Sponges have specialized cells, but they lack coordination among these cells, not true tissues.
  • Sponges have skeletons of lime (calcium carbonate), silica, or organic fibers (spongin).
  • They don't have sensory or nerve cells, thus their responses to stimuli are limited.
  • Nutrition is holozoic, meaning they take in food through phagocytosis.
  • They lack a digestive tract.
  • The interior space is called a spongocoel (paragastric cavity).
  • Choanocytes (collar cells) with flagella are present in the spongocoel for feeding and water circulation.
  • Respiration and excretion occur by diffusion.
  • Sponges reproduce asexually by budding or forming gemmules.
  • They also reproduce sexually by forming gametes.
  • They have no circulatory or muscular systems; they rely on water flow generated by choanocytes to obtain food and oxygen and remove waste.
  • About 5,000 living species are classified into three classes: Calcarea, Desmospongia, Hexactinellida, based on skeleton composition.

Cellular Structure

  • Sponges have three cell layers:
    • Pinacoderm (dermal layer): Outer layer of flattened cells.
    • Choanoderm (gastral layer): Inner layer of flagellated choanocytes.
    • Mesohyl (mesenchyme): Gelatinous matrix between the two layers, containing amoebocytes and skeletal elements (spicules or spongin).
  • Pinacocytes: Flat, leathery cells lining exterior.
  • Archaeocytes (amoebocytes): Amoeboid cells, capable of differentiating.
  • Sclerocytes: Produce spicules.
  • Porocytes: Surround canal openings (pores).
  • Spongocytes: Secrete fibrous collagen called spongin.
  • Myocytes: Contractile cells.

Sponge Types

  • Asconoid: Simplest type, small, tubular form.
  • Syconoid: More complex, with folded body wall creating channels.
  • Leuconoid: Most complex, with numerous chambers.

Nutrition

  • Sponges are filter feeders, obtaining food from the surrounding water.
  • Microorganisms and organic particles are filtered through the sponge's structure.
  • Food is phagocytosed by choanocytes and archaeocytes.
  • Some species can also capture prey with hooks, spicules, or tentacles.

Respiration and Excretion

  • Respiration occurs via simple diffusion of dissolved oxygen in the water.
  • Excretion mainly happens through ammonia diffusion.
  • Fresh water sponges use contractile vacuoles to remove excess water.

Reproduction

  • Sponges reproduce asexually through budding or creating internal buds called gemmules.
  • Gemmules are resistant to harsh conditions, facilitating survival during unfavorable periods.
  • Reproduction can also be sexual, with sponges being hermaphroditic.
  • External fertilization happens in surrounding water.
  • Internal fertilization is also possible, where sperm enters through the aqueous system.
  • Development involves blastula and amphiblastula.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

Description

Explore the fascinating world of Porifera, the phylum that encompasses sponges. Learn about their unique characteristics, including their body structure, habitat, and nutritional methods. This quiz offers insights into their classification within the animal kingdom and their evolutionary significance.

More Like This

Use Quizgecko on...
Browser
Browser