Seahorse Development

Introduction

Newborns of three syngnathid species (A) N. ophidion, (B) S. abaster, and (C) H. abdominalis. Scale bars are 2 mm.

Hippocampus (Greek, ippos = horse; kampe = curvature)

Actinopterygii (ray-finned fishes) > Syngnathiformes (Pipefishes and seahorses) > Syngnathidae (Pipefishes and seahorses) > Hippocampinae

Seahorse Development

Some Recent Findings

Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae) "We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods - early embryogenesis, eye development, snout formation, and juvenile - which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy."

Standardised classification of pre-release development in male-brooding pipefish, seahorses, and seadragons (Family Syngnathidae)

BMC Dev Biol. 2012 Dec 29;12:39. doi: 10.1186/1471-213X-12-39.

Sommer S, Whittington CM, Wilson AB. Source Institute of Evolutionary Biology and Environmental Studies, University of Zürich, Winterthurerstrasse 190, Zürich, CH-8057, Switzerland. stefan.sommer@ieu.uzh.ch.

Abstract

BACKGROUND: Members of the family Syngnathidae share a unique reproductive mode termed male pregnancy. Males carry eggs in specialised brooding structures for several weeks and release free-swimming offspring. Here we describe a systematic investigation of pre-release development in syngnathid fishes, reviewing available data for 17 species distributed across the family. This work is complemented by in-depth examinations of the straight-nosed pipefish Nerophis ophidion, the black-striped pipefish Syngnathus abaster, and the potbellied seahorse Hippocampus abdominalis.

RESULTS: We propose a standardised classification of early syngnathid development that extends from the activation of the egg to the release of newborn. The classification consists of four developmental periods - early embryogenesis, eye development, snout formation, and juvenile - which are further divided into 11 stages. Stages are characterised by morphological traits that are easily visible in live and preserved specimens using incident-light microscopy.

CONCLUSIONS: Our classification is derived from examinations of species representing the full range of brooding-structure complexity found in the Syngnathidae, including tail-brooding as well as trunk-brooding species, which represent independent evolutionary lineages. We chose conspicuous common traits as diagnostic features of stages to allow for rapid and consistent staging of embryos and larvae across the entire family. In view of the growing interest in the biology of the Syngnathidae, we believe that the classification proposed here will prove useful for a wide range of studies on the unique reproductive biology of these male-brooding fish.

Common Name - Seahorse

Country	Species
Cuba	Hippocampus erectus
Malaysia	Hippocampus erectus
Malaysia	Hippocampus histrix
Malaysia	Hippocampus kuda
Malaysia	Hippocampus spinosissimus
Malaysia	Hippocampus barbouri
Malaysia	Hippocampus comes
Azores Islands	Hippocampus histrix
Puerto Rico	Hippocampus reidi
St Helena	Hippocampus erectus
United Kingdom	Hippocampus guttulatus

Table data from Fishbase.

Developmental Stages

Then following images and staging information is from a study of N. ophidion, S. abaster, and H. abdominalis. development.

Figure 1 Early embryogenesis Descriptions of the four stages of the early-embryogenesis period, along with examples for each stage. (A) Animal-pole view of a zygote of N. ophidion ca. 45 min after mating. (B) Animal-pole view of a N. ophidion blastula during early cleavages. (C) Embryonic-shield stage in N. ophidion; the white circle represents the germ ring. (D) Primitive-streak embryo of S. abaster (dechorionated). Scale bars are 0.5 mm.

Figure 2 Eye development Descriptions and schematic drawings of stage-defining eye-structures of the three stages of the eye-development period, along with examples for each stage. (A) Optic-vesicle stage in N. ophidion. (B) Optic-cup stage in S. abaster. (C) Eye-pigmentation stage in N. ophidion. All embryos were dechorionated prior to photographing. Scale bars are 0.5 mm.

Figure 3 Snout formation. Descriptions of the three stages of the snout-formation period, along with examples for each stage. (A) S. abaster embryo (dechorionated) with ventrally developing jaws. (B) H. abdominalis larva with jaws rising frontally. (C) S. abaster larva with an elongated snout. Scale bars are 1 mm.

Figure 4 Newborns of three syngnathid species. The newborn stage represents the first stage of the juvenile period and, for the purpose of this classification, refers to the first day post-release. Shown are (A) N. ophidion, (B) S. abaster, and (C) H. abdominalis. Scale bars are 2 mm.

References

Articles

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• FishBase | Hippocampus erectus Perry, 1810 - Lined seahorse

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Cite this page: Hill, M.A. (2024, April 25) Embryology Seahorse Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Seahorse_Development

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