Journal archives for October 2017

October 03, 2017

Seahorse identity crisis?!?

iSeahorse's featured seahorse for August is… drumroll please... a mystery! It was found at Mafia Island Marine Park off the coast of Tanzania by two divers from Mafia Island Diving (posted to iSeahorse under the username mafia-island-diving). There have been plenty of Hippocampus histrix (thorny seahorse) sightings in the area, but that’s not the species seen here. While this fish is undeniably dapper, that’s where the certainty ends. At this point, our best guess is H. kuda (spotted seahorse), but coming to this conclusion hasn’t been easy as there are four main challenges.

Challenge #1: As vital as photographs are to seahorse research, there is only so much that a single snapshot can reveal. Riley Pollom, an IUCN Seahorse, Pipefish & Stickleback Specialist Group member, weighed in on the situation. “I would say that this is H. kelloggi given the shape of the coronet and the eye spines,” said Pollom. “I can’t be sure with that photo though.” The photo shows only one angle of the animal, and parts of its body are obscured by the environment. However, the pattern and colour are showcased quite marvelously.

Challenge #2: In many animal species, colour and pattern could be enough to identify an individual specimen. Unfortunately, seahorses aren’t so simple, especially since they can change colour, and some can even grow fronds to match their habitat. “I have seen that colour pattern on H. trimaculatus (three-spot seahorse) quite often,” said Pollom. “But that species isn’t known from there and is typically deeper.”

Challenge #3: Just because a species hasn’t been found living in an area, doesn’t mean it doesn’t live there - it just might not have been discovered there yet! iSeahorse plays a role in matching geographic locations to Hippocampus species. Lily Stanton, a Project Seahorse biologist, was torn between H. alatus and H. borboniensis. “The problem is that H. alatus is not known to occur on the east coast of Tanzania, and is predominantly distributed in Southeast Asia.”

Challenge #4: Brace yourself for some Hippocampus drama! H. alatus and H. borboniensis no longer exist. Don’t worry, the seahorses aren’t extinct, just the latin names. Hippocampus alatus is now referred to as H. spinosissimus (hedgehog seahorse), while H. borboniensis is considered to be H. kuda (spotted seahorse). “After much deliberation, I decided on with H. kuda,” said Stanton. “I thought it seemed to closely resemble H. borboniensis, which has been synonymized with H. kuda based on the taxonomic revision of seahorses by Lourie et al. 2016.” In the revision, nine former species were lumped with H. borboniensis into the kuda group. Stanton added,“I did, however, feel that it closely resembled H. alatus as well, which has been synonymized with H. spinosissimus.”

Dr. Sara Lourie, the Project Seahorse research associate involved with the revision, is a Hippocampus taxonomy expert. She agreed with Stanton that the fish-of-the-month closely resembles H. borboniensis, leading to a tentative diagnosis of H. kuda. “The bottom line is that H. borboniensis is a poorly understood species, as is H. alatus, neither of which are currently listed as valid,” said Lourie. In the revision, many species that were historically distinct from one another became synonymous. At present, there are 41 recognized seahorses, but that number is subject to go up or down as we learn about Hippocampus genetics, appearance, range and behaviour. The kuda group could potentially be re-divided and re-named, so if H. kuda actually represents several species, to call the mystery fish H. kuda might not be telling the full story. “I do think that iSeahorse has the potential to be a great source of information to learn more about species diversity and distribution,” said Lourie.

Part of the reason that seahorse identification, and species identification in general, is so taxing is that taxonomy itself is constantly in flux. Even what makes a species a species is subjective. Species can be designated based on different classification systems, including physical traits, the ability to produce viable offspring, and similarities at a molecular level. Scientists can debate the definition of species til the sea cows come home, but at the end of the day, there is no easy answer. Taxonomy can be messy. There is no easy answer to August’s featured seahorse conundrum, either. For now, let’s go with H. kuda, shall we?

More information:

Posted on October 03, 2017 20:52 by projectseahorse projectseahorse | 2 comments | Leave a comment

October 11, 2017

One fish, two fish... spiky fish, thorny fish...



September’s featured iSeahorse observation is a jaw-dropping pic of two fused-jawed fish! Many species of seahorse are monogamous and thus often found in pairs, as is the case here. iSeahorse user ollieclarke17 gets the photo credits for this shot, which was captured in East Timor, a country ringed by coastlines rich with marine life.

As opposed to last month’s observation, it can be said with confidence that these presumed lovebirds belong to a certain species - in this case, Hippocampus histrix, aka the thorny seahorse. While there are similar-looking species, including H. jayakari (Jayakar’s seahorse), H. barbouri (Barbour’s seahorse), H. angustus (narrow-bellied seahorse) and H. spinosissimus (hedgehog seahorse), thorny seahorses can be distinguished from the rest due to their long snout. H. histrix also has one of the largest distributions of any Hippocampus species, with a range spanning both the Pacific and Indian oceans and encompassing China, Hawai’i, and South Africa, among many other countries.

Regardless of their distinctiveness, in trade records, the name H. histrix is often used for any spiky seahorse captured in the Indo-Pacific. This complicates the data on this species’ population trends and trade frequency. However, much more is known about thorny seahorses than in the past - in 2012, their IUCN Red List status went from Data Deficient to Vulnerable . It has been determined that their population is on the downswing - an unfortunate trend, but ignorance isn’t bliss when biodiversity is on the line!

Thanks again to ollieclarke17, who is a prolific photographer. Two of his pictures were recently chosen for the #SeahorseAlphabet (check them out on Facebook, Twitter, or Instagram!) to represent the letters C (H. comes) and H (hedgehog seahorse).

Link to ollieclarke17’s tiger tail seahorse (H. comes) observation:
Link to ollieclarke17’s hedgehog seahorse (H. spinosissimus) observation.

Posted on October 11, 2017 17:52 by projectseahorse projectseahorse | 1 comment | Leave a comment