Brachyura larvae
Zoeal phase

—Cephalothorax
The main body, or cephalothorax, of a zoea is covered by a carapace with free ventral and posterolateral margins that enclose the proximal parts of incipient thoracic limbs, gill buds and internal organs (Zoea lateral view). A pair of large eyes are located anteriorly and several paired appendages are inserted ventrally. A segmented flexible abdomen terminating in a telson is attached to the cephalothorax (Zoea abdomen dorsal). The cephalothorax and abdomen are pigmented but these chromatophores fade in preserved specimens and thus are not shown in figures. Due to the arrangement of prominent spines on the carapace in the majority of larvae, zoeae of species in the area have a more or less upright triangular carapace, but in some species of Dromiidae (for instance Dromia erythropus ov), Homolidae (Homola barbata ov) and Latreilliidae (Latreillia elegans ov), zoeae have a shrimp-like carapace that is longer than wide. Typically, the carapace bears a rostral, dorsal and two lateral spines (Zoea lateral view) but other combinations are possible.

—Abdomen
The abdomen of the first zoeal stage (Zoea abdomen dorsal) is composed of five articulating somites and a terminal telson (by others the telson is considered a separate entity from the abdomen). Older zoeae acquire a sixth somite at some later stage, except in Leucosiidae (Persephona mediterranea ov) and some Pinnotheridae. On abdominal somites 2 and 3, a pair of dorsolateral processes are present in almost all species (Zoea abdomen dorsal). The posterolateral margins of somites 3-5 vary in shape from rounded to bearing subacute or acute processes. The pleopod buds arise ventrally on somites 2-6 in older zoeae.

—Telson
The shape of the telson remains more or less constant throughout development. In the majority of crab larvae the posterolateral portions of the telson are extended into conspicuous furcae (see, for instance,Stenorhynchus seticornis 3). The remaining posterior margin of the telson is formed into a slight median lobe in some Pinnotheridae (see, for instance, Pinnixa chaetopterana 1), is convex in Leucosiidae (Persephona mediterranea 2), but is variably concave in most other species. The posterior margin also bears plumodenticulate setae. Zoeae of Dromiacea have ten setae (Hypoconcha sabulosa ov, Homola barbata ov, Latreillia elegans ov), Dorippidae only two (Ethusa microphthalma 2), and in all other brachyurans studied there are six setae in the first stages (see, for instance, Clypeasterophilus stebbingi 2), with additional setae added in later stages during development in the majority of brachyrhynchs. The outer lateral spine of the telson is present in nearly all previously studied species. The dorsal spine is absent in Dromiacea (see, for instance, Latreillia elegans ov), Oxyrhynchs (see, for instance, Zaops ostreum 1), but it is developed in all stages of most brachyurans (see, for instance, Uca uruguayensis 3).

—Antennule
The antennule, or a1, (Zoeal appendages 1, Zoea lateral view) is represented by a subcylindrical exopod with an undifferentiated protopod. The exopod bears aesthetascs and sometimes additional simple setae, whose number varies with the zoeal stage.

—Antenna
The antenna, or a2, (Zoeal appendages 1, Zoea lateral view) is well developed in zoeal stages of all species in the area, except for Zaops (Zaops ostreum ov) and Persephona (Persephona mediterranea ov), where it is represented only as a small bud. Three general types of antennae are distinguished:
1. In Dromiacea occurs a broad, somewhat flattened, setose exopod, the endopod is subcylindrical and bears terminal setae (Cryptodromiopsis antillensis 1,[l][m]Introduction[/m][r]Gb. 6 General remarks on seasonality, biomass and diversity in the pelagic domain of the South Atlantic[/r] Latreillia elegans 1);
2. In Hymenosomatidae (Halicarcinus planatus 1, Halicarcinus planatus ov) and some Grapsidae (Grapsidae) and Xanthidae (for instanceMicropanope sculptipes 2 Micropanope sculptipes 1) species, the antennal exopod is absent or reduced to a small simple seta, small setose process or a minute articular process bearing 1-2 terminal simple setae;
3. In Parthenopidae, all other oxyrhynchs and brachyrhynchs the antenna is more developed - the exopod is long and often extends to the distal half of the spinous process which is well developed and reaches from less than half the length to almost the tip of the rostrum (see, for instance, Portunus spinicarpus 1 Portunus spinicarpus 2). The endopod bud can be distinguished starting in the second stage.

—Mandible
The mandible is composed of distal incisor and molar processes (Zoeal appendages 2) and in some species an endopodite bud may occur basally in the last zoeal stage.

—Maxillule
The maxillule, or mx1, is composed of an endopod and a protopod (Zoeal appendages 2); from the latter arise the basis and coxa.

—Maxilla
The maxilla, or mx2, is composed of four endites: endopod, basis and coxa, and the scaphognathite, which in all species is developed into an elongated lobe (Zoeal appendages 2). The scaphognathite margin bears a consistent number of plumose setae in the first zoeal stage but the number of setae varies within a species in later stages.

—First maxilliped
The first maxilliped, or mxp1 (Zoeal appendages 1) consists of a coxa that is often imperfectly demarcated from the adjoining basis which bears a characteristic setal pattern that in most species remains unchanged during zoeal development; from the distal portion of the basis arises an endopod and exopod. The setose endopod is 5-segmented in all species studied. The unsegmented, bisegmented or partially bisegmented exopod of all species has long plumose natatory setae distally, starting with four in the first stage, to as many as 13 in older zoeae (Brossi-Garcia and Rodrigues, 1993).

—Second maxilliped
The second maxilliped, or mxp2, (Zoeal appendages 1) is similar to the first except for the endopod which is 4-segmented in the early larval stages of Dromiacea and 3-segmented in other brachyuran zoeae studied. Exceptions include Zaops, where only two segments can be recognized, and in Persephona, in which the endopod is unsegmented.

—Third maxilliped
The third maxilliped, or mxp3, can appear under the carapace as a developing non-functional bifurcated and unsegmented structure in early zoeal stages of some species (Zoeal appendages 2) but it usually occurs in later stages in species with more zoeal stages.

—Pereopods
Developing pereopods (p1, p2, p3, p4, p5) appear as gradually growing buds under the carapace during zoeal development.