Kingdom Animalia: Phylum Porifera - Sponges

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16 Questions

What distinguishes the Eumetazoa from the Parazoa?

Eumetazoa have differentiated tissues while Parazoa lack tissues

How do sponges (Phylum Porifera) feed?

Through phagocytosis by choanocytes lining the spongocoel

Which of the following best describes the body plan of cnidarians?

Diploblastic with radial symmetry and a gastrovascular cavity

What is the distinguishing feature of the Ecdysozoa clade?

They undergo ecdysis (molting of the exoskeleton)

Which of the following statements about the phylum Acoela is correct?

They are triploblastic but lack a digestive tract

How do sponges (Phylum Porifera) reproduce?

Asexually through budding and fragmentation; sexually by releasing gametes

Which of the following statements about sponges (Phylum Porifera) is correct?

They are sessile as adults but motile as larvae.

What is the primary function of choanocytes in sponges?

To direct water flow and trap food particles.

Which of the following is a characteristic of the Radiata group?

They display radial symmetry.

What is the primary function of cnidocytes in cnidarians?

To capture prey using nematocysts.

Which of the following phyla is characterized by a trochophore larva or lophophore feeding structure?


Which of the following statements about the Ecdysozoa clade is correct?

They undergo ecdysis, or molting of their exoskeleton.

Which of the following statements about Acoela is correct?

They lack a digestive tract and absorb nutrients across their surface.

What is the primary function of the spongocoel in sponges?

To serve as a central cavity for water circulation.

Which of the following statements about cnidarians is correct?

They possess a primitive nerve net.

Which of the following statements about the embryology of the Bilateria clade is correct?

They are divided into Protostomia and Deuterostomia based on embryology.

Study Notes

Kingdom Animalia

  • Kingdom Animalia is divided into two groups: Parazoa (animals lacking tissues) and Eumetazoa (true animals with differentiated tissues)
  • Both groups likely evolved from a common ancestor that resembled modern-day choanoflagellates

Phylum Porifera - Sponges

  • Sponges are the simplest of all animals
  • They are aquatic, asymmetrical, and lack true tissues
  • Adults are sessile, but larvae have motility
  • Features:
    • Osculum: opening for water expulsion
    • Spongocoel: central cavity
    • Choanocytes: collar cells that direct water through the sponge to trap and ingest food via phagocytosis
    • Spicules: skeletal spikes of silica
  • Lack digestive, respiratory, circulatory, reproductive, or nervous system
  • Reproduction:
    • Asexual: fragmentation or budding
    • Sexual: differentiation of amboecytes; monoecious/hermaphroditic

Animal Phylogeny

  • Eumetazoa are divided into two major groups based on embryology:
    • Radiata: radial symmetry (includes Cnidaria and Ctenophora)
    • Bilateria: bilateral symmetry (includes all other animals)

Phylum Ctenophora

  • Comb jellies
  • Eumetazoa, radiata
  • Features:
    • Diploblastic
    • Lack cnidocytes
    • Complete gut: mouth and anus

Phylum Cnidaria

  • Stinging animals
  • Eumetazoa, radiata
  • Features:
    • Diploblastic
    • Endoderm: lines digestive cavity
    • Ectoderm: epidermis
    • Primitive nervous system: nerve net
    • Incomplete digestive system: gastrovascular cavity
    • Cnidocytes: specialized cell type for stinging; contain nematocysts
  • Reproduction:
    • Asexual: budding
    • Sexual: release of gametes into the water
  • Carnivorous
  • Body plans:
    • Polyp: sessile, asexual
    • Medusa: dimorphic, sexual
  • Class names:
    • Anthozoa: corals, sea anemones; polypoid
    • Scyphozoa: marine jellies; medusa
    • Cubozoa: box jellyfish; true eyes
    • Hydrozoa: both polyp and medusa forms

Animal Phylogeny (continued)

  • Bilateria are divided into two major clades, also based on embryology:
    • Protostomes: further divided into two major clades
      • Lophotrochozoa: either have a trochophore larva and/or lophophore (feeding structure)
      • Ecdysozoa: molt their exoskeleton (ecdysis); include Arthropoda and Nematoda
    • Deuterostomes: include echinoderms and chordates

Phylum Acoela

  • Eumetazoa, bilateria
  • Features:
    • Triploblastic
    • Not a protostome or deuterostome
    • Blastopore closes during development
    • Simple nervous system differs from Platyhelminthes
    • Nerve net
    • Lack digestive tract: absorbs nutrients across surface
    • Embryonic development is unique: one cell divides into two cells each of which then divide into more cells
    • Very slight cephalization

Learn about the characteristics and classification of sponges in the Phylum Porifera, which are part of the Kingdom Animalia. Explore their simple structure, aquatic habitat, and unique features such as choanocytes and spongocoel.

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