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🌊 Marine Near Threatened 🐠 Aquarium 🌡️ Tropical

Sodwana pygmy seahorse

Hippocampus nalu Short, Claassens, Smith, de Brauwer, Hamilton, Stat & Harasti, 2020
Max Length
2.2 cm
Max Weight
-
Lifespan
-
Trophic Level
3.1
Depth
12–17 m
Climate
Tropical
Resilience
High
Vulnerability
10.00/100
Typical Length
-
Depth Zone
demersal

📖 Overview

This species remains undetected because of its cryptic behaviour and diminutive size. It is observed in flat sandstone-based coral reefs comprising of low pinnacles, shallow drop offs, and sandy gullies, with the latter being exposed to strong currents. It was found loosely associating with short algal turf, used as a holdfast, which was growing on sand-covered coral bedrock separated by sandy gullies (around 2 meters wide). Ambient seawater temperature averaged ca. 24 °C during the dives, which were conducted in October of 2018. Collectors experienced strong swells on the exposed reefs of 2 Mile Reef during data collection. The holotype and paratype appeared to be a mated pair, found within approximately 60 cm distance of each other on the two dives. Behaviour of the pair was observed prior to collection which was very similar to congeners H. pontohi and H. japapigu. Several individuals, including a small juvenile (ca. 1.0 cm SL), were found in the gullies and observed to be associated with low-growth algal turf. The juvenile, retained the dark colouration of a recently settled juvenile pygmy seahorse .

Scientific Name
Hippocampus nalu
Authority
Short, Claassens, Smith, de Brauwer, Hamilton, Stat & Harasti, 2020
Habitat
Marine
Climate
Tropical
IUCN Status
NT
Max Length
2.2 cm
Depth Range
12–17 m
Trophic Level
3.1
Resilience
High
Vulnerability
10.00/100
Migration
Non-migratory
Salinity
30–40 ppt

🐟 Physical Description

Dorsal soft rays (total): 12. This species is distinguished by the following set of characters: tail rings 29-30; D 12; pectoral fin rays 10; subdorsal rings 4; there are 2 pairs of bilateral wing-like protrusions behind the head formed by a pair of large oblong spines projecting anterolaterad on the first superior trunk ridge and 1 pair of unique double cuspidate spines projecting anteriad on the second superior trunk ridge; double spine above the eyes; no spines at the sixth superior trunk and eighth inferior trunk ridges; superior trunk ridge ending with two subdorsal spines protruding laterad; posteriormost spine greatly enlarged on twelfth trunk ridge .Cross section: angular.

🌀 Behaviour

Behavioural data for Sodwana pygmy seahorse is currently being reviewed.

🦐 Diet

aquatic invertebrates
small fish
algae
detritus

🥚 Reproduction

🐣 Oviparous 📦 Batch Spawner
Spawning Season
spring-summer
Spawn Location
Pelagic
Fertilization
External

🌍 Habitat & Distribution

Marine; demersal; non-migratory; depth range 12 - 17 m . Tropical South Africa.

🌿 Ecology

Zone Preferences
🌊 Marine ⬇️ Benthic
Migration
Non-migratory
Trophic Level
3.1±0.3

📐 Morphometrics

Length–Weight Relationship: W = 0.00447 × L3 (TL)
Max TL
2.2cm
Dorsal Rays
12

🌡️ Water Parameters & Tolerance

Salinity Range
30–40ppt

🛡️ Conservation Assessment

IUCN Category
Near Threatened
Assessment Date
2023

📊 Population Risk & Fisheries

Population Resilience
High
Minimum doubling time
Fishing Vulnerability
10.00/100
Low vulnerability
Trophic Level
3.1
Predator
Climate Zone
Tropical
Described By
Short, Claassens, Smith, de Brauwer, Hamilton, Stat & Harasti, 2020

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