THE ANIMAL FILES

Spectacle case pearly mussel

No verified Chinese common name in our sources; the English name is retained.

Cumberlandia monodonta

A river mussel begins with a fish connection.

The spectaclecase is a freshwater mussel with an elongated shell and a larval stage that uses fish hosts. Adults filter food from river water, while larvae must complete a different kind of journey before becoming settled young mussels.[1]

Follow the evidence ↓
Spectacle case pearly mussel
Image: USFWSmidwest · Commons · Public domain
The long shell
Shell colour darkens with age.[1]
A fish-host stage
Larvae are called glochidia.[1]
Adult filter feeding
Algae and bacteria contribute food.[1]

The long shell

Younger shells are described as yellowish green, becoming brown or black in older animals. The outline is elongated rather than a round clam shape. A change in colour through growth does not necessarily identify a different species.[1]

A fish-host stage

Fertilised eggs develop into glochidia released into the water. A temporary parasitic stage on fish is required. Hiodon tergisus and Hiodon alosoides are confirmed hosts, and research continues into possible additional hosts.[1]

Adult filter feeding

Adults live in river substrate and filter food from the water. The animal's adult feeding is distinct from the larva's use of a fish host. Completing the life cycle needs both suitable adult habitat and access to hosts during development.[1]

A COMMON MIX-UP

Does the adult spend its life parasitising fish?

No. Fish hosts are used by the larval stage; adults are river-bottom filter feeders.[1]

TRY A LITTLE REASONING

Why could a mussel population fail to recruit young even where adults can feed?

Reveal the explanation

Larvae also need suitable fish hosts. Adult food alone does not complete the developmental cycle.[1]

Sources & editorial notes

Adapted and translated from the cited Wikipedia revisions, with source-linked reasoning. Image credit and licence are listed separately above.

Adapted and translated from Wikipedia contributors; exact revisions are linked below. CC BY-SA 4.0

  1. Wikipedia contributors — Spectacle case pearly mussel (cited revision)
  2. NCBI Taxonomy — Cumberlandia monodonta

Last fact check:

One discovery leads to another

Giant clamA clam can host part of its own food supply.Tridacna gigas ↗Pacific oysterA drifting larva becomes a permanently attached oyster.Magallana gigas ↗Roman snailThe shell has a doorway—and sometimes a temporary seal.Helix pomatia ↗