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Why are sponges not considered to have tissue level organization?

Quite a few places seem to say that sponges do not have 'true tissue' and only have specialized cells.

Unlike Protozoans, the Poriferans are multicellular. However, unlike higher metazoans, the cells that make up a sponge are not organized into tissues. Therefore, sponges lack true tissues and organs;

The Wikipedia page on sponges says -

Sponges are similar to other animals in that they are multicellular, heterotrophic, lack cell walls and produce sperm cells. Unlike other animals, they lack true tissues and organs.

I have not been able to find what defines true tissue, so I would like to understand what characteristics a group of cells must have for it to be considered proper tissue.

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  • $\begingroup$ Can you please expand your question with at least one quote from a source that uses the term "true tissue", in order to help understand your question? When I google, the term I find is "organized tissue", which may be different than you are asking about. $\endgroup$ – jakebeal Jan 24 at 13:15
  • $\begingroup$ @jakebeal I'm so sorry, I don't really know how you add a quote from a source. However, true tissue is what showed up on multiple pages when I googled 'Do sponges have tissues and organs?' $\endgroup$ – ani Jan 24 at 13:21
  • $\begingroup$ Is this the definition you mean glossary.lias.net/wiki/True_tissue ? $\endgroup$ – user438383 Jan 24 at 13:24
  • $\begingroup$ @ani You can edit your question and add text from one of the sources that you saw. To indicate a quote, you can just use quotation marks or do a ">" for a blockquote. $\endgroup$ – jakebeal Jan 24 at 13:24
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    $\begingroup$ @jakebeal thank you! I've edited the question, hope it is clearer now. $\endgroup$ – ani Jan 24 at 15:11

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