egg case

C1-C2
UK/ˈeɡ ˌkeɪs/US/ˈeɡ ˌkeɪs/

Technical/Scientific

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Definition

Meaning

A protective capsule or structure, typically tough and leathery, that contains the eggs of certain animals.

In a business or tech context, can be used metaphorically to describe a protected or encapsulated unit, module, or component.

Linguistics

Semantic Notes

Primarily a biological term; metaphorical use is very rare and context-dependent.

Dialectal Variation

British vs American Usage

Differences

No significant lexical difference. In scientific texts, the British spelling 'case' is identical to the American spelling.

Connotations

Neutral and technical in both varieties.

Frequency

Equally low-frequency in both varieties, confined to specific scientific or educational contexts.

Vocabulary

Collocations

strong
mermaid's purseshark egg caseleathery egg case
medium
empty egg casespiral egg casewhelk egg case
weak
strange egg casewashed-up egg casetiny egg case

Grammar

Valency Patterns

[to find/discover/examine] an egg caseegg case [of/from/laid by] a shark/skate

Vocabulary

Synonyms

Strong

mermaid's purse (specifically for skates, rays, some sharks)

Neutral

egg capsuleootheca (for insects)egg sac

Weak

protective casingegg holder

Vocabulary

Antonyms

free-swimming larvaelive birthnaked egg

Phrases

Idioms & Phrases

  • [No established idioms for this specific compound]

Usage

Context Usage

Business

Virtually unused. A forced metaphor might be 'the project is in its egg case phase' meaning it is protected and undeveloped.

Academic

Used in marine biology, entomology, and zoology papers to describe the reproductive structures of certain species.

Everyday

Used by beachcombers, naturalists, or in educational settings (e.g., museums, aquariums, documentaries).

Technical

Standard term in relevant biological fields for the protective capsule surrounding a clutch of eggs.

Examples

By Part of Speech

verb

British English

  • The whelk egg cases can be seen washed up on the strandline.
  • The shark egg-cased its embryos for protection.

American English

  • The skate leaves its egg case anchored to seaweed.
  • Researchers observed how the species egg-cases its young.

adverb

British English

  • [No standard adverbial use]

American English

  • [No standard adverbial use]

adjective

British English

  • The egg-case material was surprisingly tough.
  • They studied the egg-case morphology.

American English

  • The egg-case structure varies by species.
  • An egg-case fragment was found on the beach.

Examples

By CEFR Level

A2
  • We found an egg case on the beach.
B1
  • The children collected empty egg cases from the shoreline.
B2
  • Marine biologists can identify the species of shark by the shape and size of its egg case.
C1
  • The spiral, parchment-like egg case of the whelk is a common sight along the North Atlantic coast.

Learning

Memory Aids

Mnemonic

Think of a 'case' for your phone. An 'egg case' is like a tough, natural phone case, but for eggs from creatures like sharks and whelks.

Conceptual Metaphor

PROTECTION IS A CONTAINER; DEVELOPMENT IS ENCAPSULATION.

Watch out

Common Pitfalls

Translation Traps (for Russian speakers)

  • Do not translate as 'яичный кейс' or 'яичный случай'. 'Case' here means 'оболочка', 'футляр', 'капсула'. Correct translation: 'яйцевая капсула', 'кокон с яйцами'.

Common Mistakes

  • Using 'egg shell' for aquatic animals (shell is calcareous and brittle, a case is often leathery).
  • Spelling as one word: 'eggcase' (standard is two words).

Practice

Quiz

Fill in the gap
Beachcombers often find the leathery, rectangular of skates, commonly called a mermaid's purse.
Multiple Choice

What is a 'mermaid's purse' a colloquial name for?

FAQ

Frequently Asked Questions

It is standardly written as two separate words: 'egg case'.

Sharks, skates, rays, whelks, and some insects like cockroaches (where it's called an ootheca).

No, it is not used for bird eggs. For a chicken egg, you would say 'eggshell'.

It is a low-frequency, specialized term. Most people encounter it only in specific contexts like marine biology, beachcombing, or nature documentaries.