---
title: Sea otters protect kelp forests by eating the sea urchins that eat k… — Balance in a food web · tree and pragmatics
description: Sea otters protect kelp forests by eating the sea urchins that eat kelp. Who acts: Sea otters, sea urchins. A sentence of the lesson «Balance in a food web» of the world course of Mova's primary school with its dependency tree and the pragmatics of every clause.
---

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# Balance in a food web, sentence 15

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Sea otters protect kelp forests by eating the sea urchins that eat kelp.

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**Who acts:** Sea otters, sea urchins · **What happens:** protect, eat · **To what, where:** kelp forests, sea urchins, kelp

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This is a sentence of the lesson «Balance in a food web» of the world course of Mova's primary school. The page gives its syntax tree — a dependency tree in the style of Universal Dependencies — and its pragmatics clause by clause: who acts (Sea otters, sea urchins), what happens, when and where, as Mova's frames read it from the tree.

## The tree {#tree}

```conllu
# sent_id = school:world:030-balance-in-food-webs.lesson:15
# text = Sea otters protect kelp forests by eating the sea urchins that eat kelp.
# source = school lesson (ours)
# course = world
# lesson = 030-balance-in-food-webs.lesson
# annotation = Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): no change
1	Sea	sea	NOUN	NN	Number=Sing	2	compound	_	_
2	otters	otter	NOUN	NNS	Number=Plur	3	nsubj	_	_
3	protect	protect	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
4	kelp	kelp	NOUN	NN	Number=Sing	5	compound	_	_
5	forests	forest	NOUN	NNS	Number=Plur	3	obj	_	_
6	by	by	SCONJ	IN	_	7	mark	_	_
7	eating	eat	VERB	VBG	Tense=Pres|VerbForm=Part	3	advcl	_	_
8	the	the	DET	DT	Definite=Def|PronType=Art	10	det	_	_
9	sea	sea	NOUN	NN	Number=Sing	10	compound	_	_
10	urchins	urchin	NOUN	NNS	Number=Plur	7	obj	_	_
11	that	that	PRON	WDT	PronType=Rel	12	nsubj	_	_
12	eat	eat	VERB	VBP	Mood=Ind|Number=Plur|Person=3|Tense=Pres|VerbForm=Fin	10	acl:relcl	_	_
13	kelp	kelp	NOUN	NN	Number=Sing	12	obj	_	_
14	.	.	PUNCT	.	_	3	punct	_	_
```

## Pragmatics {#pragmatics}

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- form: statement
- act: assert
- voice: narrator
- polarity: none
- teacher: kept the draft

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| # | verb | tense, mood | who | what, whom | to whom | where | when | other | roles by |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | **protect** | present | Sea otters | kelp forests |  |  |  |  | vn defend-72.3 «NP V NP»: agent=Agent forest=Beneficiary |
| 2 | **eat** | gerund | Sea otters *not said here* | the sea urchins |  |  |  |  | vn eat-39.1-1 «NP V NP»: agent=Agent urchin=Patient |
| 3 | **eat** | present | the sea urchins | kelp |  |  |  |  | vn eat-39.1-1 «NP V NP»: agent=Agent kelp=Patient |

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One row per clause the reader finds. «not said here»: a role filled from the clause above. «roles by»: a VerbNet class and frame when one fits the verb, else the reader's rules on the tree.

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**Licence: [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/)**, as the whole of Mova corpus 0.4, of which this treebank (the agreed school, `mova-school-agreed-en.conllu`) is part. The lessons were written for Mova's primary school. Sentence `school:world:030-balance-in-food-webs.lesson:15`.

**The tree:** Mova annot: Rust (en) → Haiku 5.5 (medium, Batches API) patches; gates UD 2.18; agreed by treeagree rules (Stanza, Trankit, spaCy trf): no change. **The frames** are read from the tree by Mova's frames reader (`prag`) when this page is built, the lesson read in order, so a pronoun may be resolved from an earlier sentence.

See the [release 0.4](https://md.mova.elamur.ai/free/en/releases/0.4/).

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- ← previous: [Balance in a food web, 14](https://md.mova.elamur.ai/free/en/corpora/school/world/30-balance-in-food-webs/14/)
- next →: [Balance in a food web, 16](https://md.mova.elamur.ai/free/en/corpora/school/world/30-balance-in-food-webs/16/)
- ↑ back to [the lesson](https://md.mova.elamur.ai/free/en/corpora/school/world/30-balance-in-food-webs/)