Choanoflagellates

One group of heterotro phic protists with flagella, the choanoflagellates, is thought to comprise the closest relatives of the animals. The choanoflagellates are sister to the animals, and the animal-choanoflagellate lineage is sister to the fungi (see Figure 28.9) The clade consisting of fungi, animals, and choanoflagellates is called the opisthokonts.

Codosiga Botrytis Food Chain

(a) Codosiga botrytis

(b) Choanoeca sp.

(a) Codosiga botrytis

(b) Choanoeca sp.

Choanoflagellates

Stalk

Individual cell

28.28 A Link to the Animal Kingdom Choanoflagellates may be close relatives of the sponges, and thus represent a link between the protists and the kingdom Animalia. (a) The formation of colonies by unicellular organisms, as in this species, is one route to the evolution of multicellularity. (b) A solitary choanoflagellate illustrates the similarity of this protist group to a cell type present in the multicellular sponges (see Figure 32.4).

Stalk

Individual cell

28.28 A Link to the Animal Kingdom Choanoflagellates may be close relatives of the sponges, and thus represent a link between the protists and the kingdom Animalia. (a) The formation of colonies by unicellular organisms, as in this species, is one route to the evolution of multicellularity. (b) A solitary choanoflagellate illustrates the similarity of this protist group to a cell type present in the multicellular sponges (see Figure 32.4).

ChoanoflageSsJIas are colonial and are thought to be closely related to the sponges, the most ancient of the surviving phyla of animals. Choanoflagellates bear a striking resemblance to the most characteristic type of cell found in the sponges (compare Figures 28.28 and 32.4).

Sponges are also colonial rather than truly multicellular, in that they lack organized tissues and their cells can be sep-

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  • ULRIKE
    What kingdom are choanoflagellates?
    8 years ago

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