# Horseshoe SOS

> Identification guide and conservation resource for horseshoe crabs. (iPhone/iPad app by Naturedigger LLC.)

- Source: https://appshunter.io/ios/app/horseshoe-sos/id1000186616 (this page in markdown: same URL + `.md`)
- Developer: [Naturedigger LLC](https://appshunter.io/developer/658672412)
- Category: Education, Reference
- Price: Free
- Rating: 5.00/5 from 5 App Store ratings · 3 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 35 MB
- Languages: English
- Released: 2015-09-02
- Data updated: 2026-06-10
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/horseshoe-sos/id1000186616/reviews.md

## What is Horseshoe SOS?

Horseshoe SOS was developed by Naturedigger, LLC as an identification guide and introduction to one of our most unique and ancient marine animals. 

Horseshoe SOS includes:

•	Identification and geographic ranges of all four horseshoe crab species present in North America and Asia

•	An Atlantic horseshoe crab Gallery filled with high res images of spawning crabs, eggs and juvenile crabs, as well as an ID section with annotated images of dorsal and ventral views, horseshoe crabs' unique eyes and much more...

•	A Conservation section that lists organizations involved in horseshoe crab education and conservation. Browse their profile pages to see how their programs help horseshoe crabs and how they include the public in horseshoe crab conservation. (If an organization collects data using Horseshoe SOS, you will see a "New Report" tab in their profile. If a report tab is absent, the organization either doesn't collect data using citizen scientists or you must visit their website to input data)

•	A Threats section spotlighting both natural and unnatural threats facing horseshoe crabs 

•	An awesome FAQ section that answers many pressing questions about horseshoe crabs such as: "Why are there so many dead horseshoe crabs on the beach?" and "Where and when are the best times to see horseshoe crabs spawn?" and "Why is a horseshoe crab's blood blue?" You will learn several ways the public can have a major, positive impact on horseshoe crab populations. We love to hear from you, so please use the Feedback email in the slide out menu of the app to submit your own questions for our FAQ section!

•	A Research section for in-depth information about horseshoe crab conservation, population and management. You can access ERDG's searchable database in this section as well 

•	Reporting tagged horseshoe crabs to the US Fish and Wildlife Service (USFWS). Go to the Report Tag button on the main navigation menu and fill in the fields (especially the tag number) take a photo, then send your report, it's that easy! USFWS really appreciates these "resightings" and will send information about where and when the horseshoe crab was originally tagged and released

## Key features

- Species identification and geographic ranges
- High-resolution image gallery
- Conservation organization profiles
- Threats to horseshoe crabs
- FAQ on horseshoe crab behavior and biology
- Research database access
- Report tagged horseshoe crabs

## Recent user reviews (3 of 3)

All indexed reviews: https://appshunter.io/ios/app/horseshoe-sos/id1000186616/reviews.md

### 5/5 — Good amount of info on this amazing animal.

*2020-11-03, version 3.3*

Where I live these are not any. I show this info after getting some exoskeletons from abroad as proof of this unique living fossil. The most perplexing thing is regardless of its looks, this organism don’t have any means of defense but it’s carapace. A passive defense of sorts. It’s life is helping others more than itself. That its beauty

### 5/5 — Excellent info on this ancient species

*2019-05-06, version 3.1*

This app is top notch. It contains excellent information on horseshoe crabs, great pictures, some research and a list of organizations that are trying to help horseshoe crabs. The FAQ answers all if the most common questions people have about these wonderful creatures.

### 5/5 — Horseshoe Crabs

*2017-05-07, version 2.6*

Great app.

## Frequently asked questions about Horseshoe SOS

### What horseshoe crab species does Horseshoe SOS cover?

Horseshoe SOS provides identification and geographic range information for all four horseshoe crab species found in North America and Asia. This includes detailed insights into their unique characteristics and habitats.

### Can I report horseshoe crab sightings with Horseshoe SOS?

Yes, you can report tagged horseshoe crabs directly to the US Fish and Wildlife Service through the app. The 'Report Tag' feature allows you to easily submit tag numbers and photos for these valuable 'resightings'.

### How does Horseshoe SOS help with horseshoe crab conservation?

The app features a dedicated Conservation section with profiles of organizations involved in horseshoe crab education and conservation. It explains how their programs help horseshoe crabs and how the public can get involved.

### What kind of information is in the Horseshoe SOS FAQ section?

The FAQ section addresses common questions about horseshoe crabs, such as why they might be found dead on beaches, the best times to see them spawn, and the reason for their blue blood. It also highlights ways the public can positively impact horseshoe crab populations.

### Is Horseshoe SOS suitable for young children?

Horseshoe SOS has an age rating of 4+, making it appropriate for young children to explore and learn about marine life. The app is designed to be educational and engaging for a broad audience.

### How often is Horseshoe SOS updated?

The app was last updated on February 8, 2020, with the latest version being 3.3. While updates may not be frequent, the core information provided remains valuable for learning about horseshoe crabs.

### What devices support Horseshoe SOS?

Horseshoe SOS is available on iPhone, iPad, and iPod devices. This ensures accessibility for a wide range of Apple users interested in marine biology.

### Does Horseshoe SOS offer offline access to information?

The description does not specify offline access. However, identification guides and educational content are often designed for use in various environments, potentially including offline scenarios.

## Version history (last 1 release)

### 3.3 — 2020-02-08

•Bug fixes

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## More apps by Naturedigger LLC

- [Rash Plants](https://appshunter.io/ios/app/rash-plants/id658672409)
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- [Knotweed!](https://appshunter.io/ios/app/knotweed/id1038152166)

All apps by Naturedigger LLC: https://appshunter.io/developer/658672412

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*