Classification

Photo used with permission by Paddy Ryan, showing its defining characteristics

Taxonomy (Encyclopedia of Life)
 Domain: Eukarya
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii
Order: Gasterosteiformes
 Family: Syngnathidae
Genus: Hippocampus
Species: Hippocampus bargibanti

Synapomorphies of these groups:
Eukarya: H. bargibanti is a member of the domain Eukarya - “Eu” meaning “true” and “karya” meaning “nucleus.” All Eukaryotes have cells containing a nucleus and membrane-bound organelles.
Animalia: What makes an animal an animal? Members of the Animalia kingdom have the synapomorphy of multicellularity and cells lacking a cell wall. They are heterotrophic, meaning they rely on other organisms for food.
Chordata: H. bargibanti belongs in the phylum Chordata because it has the synapomorphies of notochords and dorsal nerve cords. As it is a member of the Chordata, it is a deuterostome - meaning that its anus develops prior to its mouth - and a triploblast - meaning it contains an endoderm, ectoderm, and mesoderm with bilateral symmetry. It is also a member of the subphylum vertebrates because it has vertebrate structures.
Actinopterygii: The class Actinopterygii includes all ray-finned fishes (Encyclopedia of Life).
Gasterosteiformes: This order is not heavily researched, but includes trumpet fishes, sticklebacks, snipefish, and sea moths (Lourie and Foster 2004). A further breakdown and phylogenetic analysis of this order that shows where the Syngnathidae family falls in comparison to other members of the Gasterosteiformes is presented in a phylogenetic tree below.
Syngnathidae: This family includes three major groups: pipefishes (which have the appearance of stretched-out/flat seahorses), seadragons (similar to seahorses, but have appendages that camouflage them in seaweed), and seahorses. All three groups have the synapomorphy of undergoing male pregnancy (Lourie and Foster 2004). More information on this incredible male pregnancy can be found here.
These two images show the other two major groups in the Syngnathidae family. The pipefish and seadragon are the closest living relatives to the genus Hippocampus, or seahorses.

Pipefish, a close relative, photo used with permission by Paddy RyanSeadragon, a close relative,pPhoto used with permission by Paddy Ryan

Hippocampus: Pipefishes, seadragons, and seahorses then differentiate at the genus level - H. bargibanti is in the genus Hippocampus along with all other species of seahorses because of their synapomorphies of having heads at right angles to trunks and the presence of pre-hensile tails. Seahorses also have a synapomorphy in the lack of a caudal fin (Teske, Cherry, and Matthee 2004). This genus is said to have existed for 20 million years. Currently, there are 32 different identified species of seahorses, while some scientists estimate there to be 50 in total (Lourie and Randall 2003).
Hippocampus bargibanti: Finally, at the last level of taxonomy, its species name is H. bargibanti. There are a number of characteristics that set this species of seahorse apart from the others. It has a maximum height of only 2.4cm (most seahorses fall within the range of 10cm to 30cm, so this species is tiny in comparison) and has three trunk rings, along with an extremely short snout. It is very closely related to two other species of seahorses: H. minotaur and H. denise (Lourie and Foster 2004). H. denise is shown below. Many similarities can be seen, most notably in the small stature and camouflage.

Hippocampus denise, another pygmy seahorse, photo used with permission by Paddy Ryan

 Meaning of name

 So where did the name Hippocampus bargibanti come from? “Hippos” has the root meaning “horse,” while “kampos” means “sea monster.” This species was discovered in 1969 by scientist Georges Bargibant, from which the specific epithet of “bargibanti” came from (Lourie and Randall 2003).

Common names: H. bargbanti is also known by its common names, often times being most generally referred to as a pygmy seahorse. This is misleading, however, as there are other species of pygmy seahorses - seven in total (Lourie and Foster 2004). It is also commonly referred to as “Bargibant’s seahorse,” again after the scientist who discovered this species in 1969 (Lourie and Randall 2003).

Phylogenetic trees:

Phylogenetic breakdown of the genus, created by website author 

This phylogenetic tree shows where H. bargibanti falls in relation to other species of seahorses. To learn more about another closely related Hippocampus species, visit Hippocampus kelloggi.
The tree was created by one of this website's authors, Kelly, using information from:
Teske, P. R., M. I. Cherry, and C. A. Matthee. 2004. The evolutionary history of seahorses (Syngnathidae: Hippocampus): molecular data suggest a West Pacific origin and two invasions of the Atlantic Ocean. Molecular Phylogenetics and Evolution 30(2):273-286.

This phylogenetic tree shows where the family Syngnathidae falls (which includes all species of the genus Hippocampus) within the order Gasterosteiformes.
This tree was created by one of this website's authors, Kelly, using information obtained from:
Wilson, A. B., and J. W. Orr. 2011. The evolutionary origins of Syngnathidae: pipefishes and seahorses. Journal of Fish Biology 78: 1603-1623.

Next, learn about this pygmy seahorse's habitat!

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