Table 2 Historical summary of the midgut caeca: denomination, derivation, and potential role for the anterior and posterior midut caeca in different decapod taxa. The proposed digestive organ from which the midgut caeca derivate is indicated: HGT, hindgut tract; MGT, midgut tract; MHJ, midgut-hindgut junction; STO, stomach. N.A. “Species” indicates that several species were included in the study and results were general for higher taxa. N.A. in remaining columns indicates that such topic was not available in the referenced study

N.A.

Brachyura

coecums pyloriques

STO

coecums postérieurs

MHJ

secretion

[11, 67]

N.A.

Brachyura

long membranous appendages

MG

N.A.

N.A.

N.A.

[68]

Astacus astacus

(Linnaeus, 1758)

Astacidea

caecum

MG

N.A.

N.A.

N.A.

[69]

Nephrops norvegicus

(Linnaeus, 1758)

Astacidea

dorsal caecum

MG

dorsal diverticulum

MG

absorption inconclusive

[36]

Pagurus bernhardus

(Linnaeus, 1758)

Anomura

anterior caeca

MG

posterior caecum

MG

inconclusive data

[55]

Spiralothelphusa hydrodroma

(Herbst, 1794)

Brachyura

midgut caeca

MG

hindgut caecum

HG

absorption

[12]

N.A.

Brachyura

N.A.

N.A.

posterior tubular gland

MG or HG

secretion inconclusive

[70]

N.A.

Brachyura

N.A.

N.A.

posterior diverticulum

HG

osmoregulation

[71]

Metapenaeus bennettae

Racek & Dall, 1965

Dendrobranchiata

anterior diverticula

MG

posterior diverticulum

MG

secretion and osmoregulation

[63]

Penaeus chinensis

(Osbeck, 1765)

Dendrobranchiata

intestinal caecum

MG

N.A.

N.A.

secretion

[72]

Homarus gammarus

(Linnaeus, 1758)

Astacidea

anterior diverticulum

MG

posterior diverticulum

MG

intracellular digestion

[15, 56]

Pachygrapsus crassipes

Randall, 1840

Brachyura

N.A.

N.A.

posterior midgut caecum

MG

inconclusive

[73]

N.A.

Brachyura

anterior midgut caeca

MG

posterior midgut caecum

MG

diverse functions

[31]

Metacarcinus magister

Dana, 1852

Brachyura

anterior midgut caeca

MG

posterior midgut caecum

MG

osmoregulation

[59]

Metacarcinus magister

Dana, 1852

Brachyura

anterior midgut caeca

MG

posterior midgut caecum

MG

digestive processes

[37]

Menippe rumphii

(Fabricius, 1798)

Brachyura

midgut caeca

MG

hindgut caecum

MHJ

N.A.

[58]

Portunus sanguinolentus

(Herbst, 1783)

Brachyura

midgut caeca

MG

hindgut caecum

MHJ

digestion & absorption

[60]

Penaeus setiferus

(Linnaeus, 1767)

Dendrobranchiata

anterior midgut diverticulum

MG

posterior midgut diverticulum

MG

inconclusive

[33, 64]

Paralithodes camtschaticus

(Tilesius, 1815)

Anomura

anterior midgut caeca

MG

posterior midgut caecum

MG

nutrient absorption inconclusive

[32]

Maja brachydactyla

Balss, 1922

Brachyura

anterior midgut caeca

MG

posterior midgut caecum

MG

active secretion observed

Present study