Lagoon Marine Life in Sebastian, Florida

The Indian River Lagoon off Sebastian holds seagrass, oysters, clams, crabs, sea stars, rays, sharks, dolphins, manatees and sea turtles, part of an estuary where more than 4,000 species of animals and plants have been documented.

That count comes from the Indian River Lagoon National Estuary Program, which says experts have documented more than 4,000 species living in the lagoon (One Lagoon). The same program puts the figure above 4,400 when the whole watershed is included (One Lagoon animals and plants). The FDEP list for the Indian River-Malabar to Vero Beach Aquatic Preserve, the state-protected water off Sebastian, gives a short version: oysters and horseshoe crabs, wading birds, seabirds and shorebirds, bottlenose dolphins and West Indian manatees, green and loggerhead sea turtles, and redfish, black drum, tarpon, snook and mullet (FDEP).

Many of those animals have their own Digital Towns pages, from snook and sheepshead to bottlenose dolphins and blue crabs. This page is the field guide one level up: which groups of animals share the lagoon at Sebastian, how many kinds of each the lagoon holds, and where along the Sebastian shore each group turns up.

The lagoon at Sebastian is diverse because the Indian River Lagoon straddles the boundary between temperate and subtropical waters, and Sebastian Inlet lets ocean animals move in and out of the estuary.

The estuary program describes the lagoon as straddling the transition zone between cold temperate and warm subtropical provinces, a place where temperate, subtropical and tropical species mingle with ample food, shelter and space (One Lagoon). It runs through seven counties, Volusia, Brevard, Indian River, St. Lucie, Martin, Okeechobee and Palm Beach, and Sebastian sits near the middle, where the Indian River County line meets Brevard at Sebastian Inlet.

The scientific record behind the counts is the Indian River Lagoon Species Inventory, curated by the Smithsonian, which documents the biodiversity of the 156-mile estuary along the Atlantic coast (IRL Species Inventory). On October 11, 2026, its home page listed 12,361 total taxa. Numbers like 4,000 and 4,400 are rounded summaries of that kind of inventory, which is why different agency pages quote different totals.

The inlet matters at the local scale. In its fish series, the Sebastian Inlet District quotes biologist Dr. Grant Gilmore listing pinfish, pigfish, mojarras, grunts, snappers, sardines, anchovies, shrimp and blue crabs as small migrators that seldom enter the fishery but feed the top predators (Sebastian Inlet District). The same tidal exchange through Sebastian Inlet carries ocean visitors such as eagle rays and jellyfish into the lagoon side of the inlet.

Near Sebastian the lagoon's small animals include about 160 kinds of bivalves, eight fiddler crab species, horseshoe crabs, and sea stars, urchins and pistol shrimp recorded at Sebastian Inlet.

Bivalves are the biggest group. The estuary program counts about 160 species of bivalves in the lagoon, among them clams, oysters, mussels, arks, cockles and coquina, and notes that they clear the water as they feed (One Lagoon animals and plants). Oysters off Sebastian have their own restoration story, told on the Digital Towns oyster reef page; the Sebastian Inlet District has photographed pelicans gathered on an oyster reef on the flood shoal side of Sebastian Inlet (Sebastian Inlet District).

Crabs line the shore. The program lists eight species of fiddler crab in the lagoon; the males wave one oversized claw, and the crabs feed on decaying mangrove leaves, algae and bacteria along the Sebastian mangrove fringe (One Lagoon). Blue crabs share the same water and are the lagoon's main recreational crab.

Horseshoe crabs are older than either. The FWC says they have existed nearly unchanged for at least 445 million years and are more closely related to spiders than to true crabs. In Florida they can nest year-round, with peak spawning in the spring and fall, and most nesting happens during high tides around a new or full moon (FWC). FDEP names horseshoe crabs among the animals of the aquatic preserve off Sebastian (FDEP).

The rocks and sand flats of Sebastian Inlet add reef animals. The district's photo record from the inlet shows the orange-ridged sea star, the nine-armed sea star on the flood shoal side, a rock-boring urchin, a pistol shrimp, a whelk and the cannonball jellyfish (Sebastian Inlet District wildlife page).

Around Sebastian, the larger lagoon animals are rays and young bull sharks, bottlenose dolphins and manatees, green sea turtles feeding on seagrass, and diamondback terrapins in the brackish marshes.

Rays are more varied than most visitors expect. The estuary program counts ten species of rays in the lagoon, including the manta, spotted eagle and cownose rays, and says rays find buried prey by sensing electric fields (One Lagoon). A spotted eagle ray appears in the Sebastian Inlet District's photographs from the inlet, alongside a stargazer, a bottom fish the district notes can deliver an electric shock (Sebastian Inlet District).

Sharks use the lagoon as a nursery. The program calls the Indian River Lagoon a vitally important nursery region for bull sharks: females enter in spring to give birth, pups are born in seagrass beds and near mangroves, and young sharks stay until they reach about 6 feet (One Lagoon).

Mammals and turtles are the most watched. Florida State Parks says Atlantic bottlenose dolphins are commonly seen in the water around Sebastian Inlet State Park, that manatees inhabit those waters from March to October, and that green sea turtles feed in the lagoon seagrass beds and can be seen on the reefs off the McLarty Treasure Museum (Florida State Parks). Diamondback terrapins, a less familiar reptile, prefer the brackish salt marshes and mangroves of estuaries rather than fresh water, according to the estuary program (One Lagoon). Manatees, dolphins and sea turtles each have their own Digital Towns pages for Sebastian.

In the lagoon near Sebastian, the U.S. Fish and Wildlife Service names the green sea turtle, Florida manatee and wood stork as federally protected and the reddish egret and tricolored heron as state protected.

Those species are listed on the Pelican Island National Wildlife Refuge page, which says thousands of species inhabit the brackish Indian River Lagoon around the refuge off Sebastian (USFWS). The same page records that in 1993 the refuge was recognized under the Ramsar Convention on Wetlands as a Wetland of International Importance, in part for its support of endangered species and large assemblages of migratory birds.

The water itself is protected too. FDEP lists the Indian River-Malabar to Vero Beach Aquatic Preserve as established in 1970 and covering 28,000 acres in Brevard and Indian River counties, and says its conservation work includes protecting bird nesting areas, planting mangroves, restoring oyster reefs and surveying seagrass (FDEP).

Hard times are part of the record. The estuary program says an unusual mortality event was declared for manatees in 2021, when more than 1,100 manatees died of starvation in the Indian River Lagoon, and that the state closed the event in 2025 (One Lagoon). The program ties the lagoon's food web to seagrass, of which it counts seven species.

Lagoon animals near Sebastian are easiest to see at Sebastian Inlet State Park, the Pelican Island National Wildlife Refuge trails on the Jungle Trail, and the Environmental Learning Center at 255 Live Oak Drive in Vero Beach.

At Sebastian Inlet State Park, Florida State Parks names the Bayside Marina docks as a place for bird, manatee and dolphin viewing year round. Snorkeling and diving are allowed in park waters except under the Sebastian Inlet Bridge and in the boat channel; snorkelers must stay within 100 feet of a dive flag, keep 50 feet from manatees, and spearfishing is not permitted (Florida State Parks).

On Pelican Island National Wildlife Refuge, Bird's Trail allows bank fishing on the lagoon side, and the refuge lists blue crab, red drum, snook and tarpon among the most popular catches (USFWS trails). In winter the refuge says white pelicans migrate south to Pelican Island, along with wintering ducks such as red-breasted mergansers, blue-winged teal and northern shovelers (USFWS species).

For animals seen up close, the Environmental Learning Center describes itself as a 64-acre nature center on the Indian River Lagoon with boardwalk trails, aquariums and a touch tank; in October 2026 adult admission was $10, with $8 for seniors and military and $5 for children 2 to 11 (Environmental Learning Center). FDEP gives fall and spring as the best seasons to visit the aquatic preserve off Sebastian (FDEP).