Fish identification archive / Marcus' aeolid

Marcus' aeolid

Coryphellina marcusorum

Fun facts for your next surface interval

Published accounts place this species on both sides of tropical America. [source]
The rhinophores have a textured rear surface made of small papillae. [source]
The Blue Heron Bridge diary’s individual was estimated at just 6–10 mm. [source]

Florida and local context

Florent Charpin’s identified Marcus’ aeolid photograph explicitly gives Blue Heron Bridge, Florida as its location.

A documented past record does not establish present abundance or guarantee an encounter.

Sources: Florent’s Guide: Marcus’ Aeolid, Blue Heron Bridge photograph

How to recognize this animal

Marcus’ aeolid has a translucent pink-to-orange body with conspicuous purple bands near the pale tips of its cerata and head appendages. The rhinophores carry many small papillae on their rear surfaces, a useful contrast with smooth-rhinophore aeolids. Some ceratal tips look yellow instead of white. In a photograph, compare the repeated color pattern across several structures rather than relying on one blurred purple ring.

Sources: Australian Museum Sea Slug Forum: Flabellina marcusorum

Size and life stages

Florent’s guide gives a length up to 25 mm; the Australian Museum account reports 30 mm. Treat those as differing published upper lengths rather than combining them into a claim that every adult reaches three centimeters. The May 2025 Blue Heron Bridge diary estimated its pictured animal at only 6–10 mm. Small local individuals can therefore look quite different in scale from a guidebook’s largest example.

Sources: Australian Museum Sea Slug Forum: Flabellina marcusorum; Florent’s Guide: Marcus’ Aeolid, Blue Heron Bridge photograph; Laura Kushner: DIVE! DIVE! DIVE! (18 May 2025)

Habitat and where to look

Accounts describe animals among rocks, crevices and rock-wall growth in shallow subtidal water. Hydroid-bearing surfaces are relevant because hydroids are their food. The local photograph establishes Blue Heron Bridge occurrence, but neither that image nor the general habitat account identifies a dependable spot within the dive site. Inspect accessible surfaces without lifting rocks or peeling growth away.

Sources: Mexican Marine Life: Marcuses’ Aeolid; Florent’s Guide: Marcus’ Aeolid, Blue Heron Bridge photograph

Range and local context

This species is reported from both the tropical western Atlantic and the eastern Pacific. Florent’s guide includes Florida and the Caribbean as well as Pacific Mexico and Central America. Its Blue Heron Bridge photograph is explicitly captioned with that Florida locality even though the web page sits within an Eastern Pacific guide. Use the photograph’s location, not the website category, when interpreting that record.

Sources: Florent’s Guide: Marcus’ Aeolid, Blue Heron Bridge photograph

What is on the menu?

Marcus’ aeolid eats hydroid polyps, according to SeaLifeBase. Finding it close to a colony is consistent with that diet, but proximity alone does not prove feeding. A useful observation records mouth contact and the identity of the colony if that can be established without collecting either animal. The sources here do not identify its particular prey at Blue Heron Bridge.

Sources: SeaLifeBase: Coryphellina marcusorum

Daily habits and behavior

Its delicate back projections are part of the living animal, not plant growth attached to it. As general aeolid biology, cerata contribute to respiration and contain digestive structures. Watch from a fixed position rather than following so closely that the camera or your fins disturb the substrate. No reliable local daily activity pattern or seasonal abundance estimate was verified.

Sources: Australian Museum Sea Slug Forum: Cerata in aeolids; Museums Victoria: Victoria’s nudibranchs

Mating and the next generation

Nudibranchs are simultaneous hermaphrodites, carrying male and female reproductive organs. This is group-level context, not a verified account of this species’ mating sequence in Florida. The consulted sources do not justify publishing a local egg-laying season, incubation period or clutch size. Nearby eggs should remain unidentified unless a stronger association is documented.

Sources: Western Australia Department of Primary Industries: Nudibranchs

Look-alikes and identification traps

Purple-tipped aeolids are not all Marcus’ aeolids. The museum account specifically notes the similarly colored western African Flabellina arveloi, illustrating why color alone can mislead. For local photographs, preserve detail of the rhinophores and entire back. Flabellina marcusorum is the historical combination of this species, not an additional species alongside Coryphellina marcusorum.

Sources: Australian Museum Sea Slug Forum: Flabellina marcusorum; WoRMS / MolluscaBase: Coryphellina marcusorum

Observe without disturbing

Avoid touching the cerata or using a pointer to steer the animal. Record an approximate length only when there is a safe, noncontact scale reference. Share a sharp image with its actual locality and date, and keep uncertain identifications tentative. An unobstructed side view is useful only if you can obtain it without repositioning the slug.

Harvest, protection and eating safety

Live-only ornamental collection; no collection at Blue Heron Bridge

Yellow means legal or safety conditions require attention. It is not an edible badge or permission to take an animal.

This color is a qualified summary, not permission to collect or a guarantee that a particular animal is safe to eat.

Can it be hunted or harvested?

Marcus' aeolid falls under Florida’s expressly named nudibranch/sea-slug category. A recreational saltwater fishing license is required unless exempt. Where collection is lawful, the animal must be landed alive and maintained alive in a suitably sized circulating, aerated or oxygenated system. The recreational limit is five of this species within 20 marine-life organisms per person per day; the two-day possession limit is ten of this species within 40 total. Recreational sale is prohibited. No species-specific size limit is stated in the reviewed marine-life table.

Florida seasons and areas

The designated Blue Heron Bridge Special Marine Life Area, including Phil Foster Park and its mapped surrounding waters, is closed to collection of listed tropical ornamental marine life. Narrow motorized-vessel transit and landing exceptions concern animals lawfully taken elsewhere, not collection here. The Florida marine-life requirements also apply in adjacent federal waters. No species-specific annual closed months are stated in the reviewed marine-life table. Biscayne National Park, state parks, wildlife refuges and Florida Keys sanctuary zones can impose additional closures; check the actual location before collecting.

Can it be speared?

No recreational spearing under these live-only marine-life requirements. Collection uses authorized nonlethal hand/net/slurp-gun methods, subject to species and site restrictions. Quinaldine is prohibited.

Is it safe to eat?

This is live-only ornamental collection, not food harvest. Do not kill a collected animal for a meal. No recipe or safe-to-eat claim is provided.

The regulatory wording uses the older umbrella “Subclass Opisthobranchia.” Modern taxonomy uses different higher groups; the rule expressly names nudibranchs/sea slugs. This is not permission to collect substrate, host colonies or other animals.

Palm Beach is Atlantic Florida. Do not transfer Atlantic guidance to the Gulf, Monroe County, or federal waters without checking the applicable rules.

Before you act: Confirm the species, date, exact management area, state or federal waters, gear, licenses and current local closures. A local occurrence record never grants permission to take an animal.

Official rules and health guidance

Reviewed 2026-11-11. Rules and advisories can change; check the linked authorities before acting.

Identification and source cautions

Published upper length differs: 25 mm in Florent’s guide, 30 mm in Sea Slug Forum.
Specific local prey, spawning season and abundance unverified.

Sources and review

Biology and taxonomy reviewed 2026-11-11. Photographs on cited sites are reference material and are not reproduced here.

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